welcome to the site!

downstairs bath - if that's a door between the 2 areas i don't see the need for it. more problems with kids and would block the window light from the first part.

the mstr bath - I think a shower only is fine there unless 1 of you really wants a tub. I think I'd consider a 1/2 wall between the vanity and the toilet. a full wall would be fine also - or 1/2 way up and then glass / glass block up to the ceiling. definitely the double sink. otherwise it looks fine to me.

keep plumbing on interior walls if possible unless you are in FL (do they get freezing temps ever?) even in AZ it can get cold enough to be glad piping is on interior walls.

upstairs bath - I don't see the need for the inner door at all. not in a kids bath especially. If the little area between the vanity and toilet is another closet and you can do w/o it, I would and put in a bigger vanity w/ possibly 2 sinks and a stack of drawers in it also.
if more than 1 kid 2 sinks will help at tooth brushing time etc. and when they get older. the drawers will be needed for things when little and when older (girls - barrettes, brushes etc). and I'd extend the wall between toilet and vanity out just a bit more (same with dwnstairs and mstr)

Thank you so much, desertsteph! I hadn't even thought about a wall between the toilet and vanity in any of the bathrooms. The vanity we purchased for the master bath is one of those furniture looking pieces. This is what it looks like now (minus the fixtures) but it will be refinished with a white-ish or light gray antiqued look; not exactly sure about the details yet. Would a 1/2 or full wall look ok next to it? I guess it will already have a wall on one side... And thanks again for all your help. You brought up several issues involving children I never would have thought of. If you have any more tips I would love to hear them!

We can't decide whether we should keep and resurface the current bathtub or replace it with a glass enclosed standing only shower. We are kind of leaning toward the shower only option because we feel like the glass enclosure would open up the room more;

I think you've got plenty of space in an 8' wide room that a tub shouldn't make it feel claustrophobic. Taking down the wall between the sink and tub/toilet will do the most to open it up. That said, if you prefer a shower over a tub, then by all means do that.

however, we aren't really sure how to design the shower area. Should the glass go all the way to the floor or should there be a partial wall in the area next to the shower door?

A wall will make it feel more closed in/cozy/private and glass will make it feel more open/less private. Some people like to show off their beautiful tile work. Others don't like to feel out in the open with a wall of glass. Depends on which you prefer and are more comfortable with.

Would it be best to relocate the shower head to the exterior wall (same wall as window) or should we keep it where it is (on the wall next to that closet)?

I don't see any reason to do so, and it would just incur extra plumbing costs, for both the water supply and the drain.

If so, could it be designed in such a way to eliminate the need of a shower door?

You generally need a wider shower to do that.

And furthermore, is it even smart to keep everything in the same general location as it is now or is there a better layout option all together?

It's smart in terms of cost to keep everything in the same location. And I don't see any problems with your current/proposed layout, in terms of wasted space or awkward configurations. If it were me, I'd leave everything where it is.

that is an BEAUTIFUL vanity! i don't think i'd want to look at it and see an ugly toilet right next to it. Unless someone makes one that 'matches' it - lol!

i think i'd take the wall all the way up or up to where the wall changes behind it in the pic and then have a piece of leaded glass go from there up to the ceiling.

so many people are closing the toilet off completely - I don't really like that as much but do like the wall/partial wall for a bit of privacy should someone happen to walk in not knowing you are in there.

I had middle of doorway swinging doors yrs ago between the vanity / linen closet side and the back part with the tub and toilet. I did like those and surprisingly never had a problem with any of the kids and the doors. It was mostly used by me and dd. the 'boys' had another bathroom to use.

now I look back and think I must have been nuts - lol!

when I moved to CA I had a sliding door between the vanity(open to the mstr bdrm) and the tub/shower and toilet. it was very small in there...and it was ok I guess. there wasn't room for any other type of door there.

i think the doors between sections really close off the room but i think the wall/partial one is a good thing for privacy.

if the tub/showers don't have the temp control fittings and you have to change anything with the pipes/fittings i'd put in the temp control ones. Having those especially with kids would be a real safety feature.

I am doing a similar renovation. Since I have not yet figured out how to post pictures, I will try to explain my plan which I am very happy with. At the entrance of the master bath, the toilet is to the left and the linen closet to the right opposite the toilet. They are both aligned. I have a walk-in shower adjacent to the toilet, and two sinks opposite the shower and adjacent to the linen closet.

The toilet is separated from the shower like this -- I have a seat in the shower, the wall of which separates the shower from the toilet. Over the seat I have a glass wall going up to the ceiling. So the toilet is separated, and the shower is enclosed. In the area where you sit on the seat, the glass wall turns a corner and covers the entire seat. Hard to explain but hope it makes sense. My bathroom is not yet built, but this is how it is planned.

Regarding the pocket door, my contractor said that he has had several problems with pocket doors. My architect said that it depends on the hardware you use, and if you don't use the door that often its okay to do a pocket door. I think its a good idea to have a pocket door between the toilet area and the shower area - that way if you are in the shower the toilet can still be used. A pocket door will keep the space more open too, whereas the door may make the size seem smaller. Hope this helps! If it doesn't make sense, I will try to post my bathroom plan.

BTW I just realized that if you are doing a pocket door inside the bathroom its probably more practical to have a sink opposite the toilet to wash hands. I am not doing a pocket door to separate my bathroom so can do a linen closet opposite the toilet. I prefer a larger vanity anyway to accommodate two sinks, and for me the best was opposite the wide shower.

Since you have the second closet and the bathroom isn't large enough for a separate shower and tub, I'd borrow some of the closet for a nice walk-in shower. Part of the walls can be glass on top.