A few things matter here first...what's the budget you have for this room? Secondly since resale is an issue for you, what's common in your competition?

Fiberglass walls are tacky (IMO) you can build in shelves in a tile surrounding. Tile is a higher value item but it depends on what your neighbors will have. I am doing a rental and wouldn't consider using the fiberglass insert things...we're middle market.

I'd upgrade the tub to an air jet tub. Jacuzzi sells a nice one for less than $800. It's nice for resale to show that upgrade.

I wouldn't even consider vinyl floor tiles either, and I'm not sure what market I would consider that in....I just wouldn't do it. It looks cheap. If you can afford to do otherwise, use at least an inexpensive tile.

It does matter! Kitchens and baths sell homes. I put my highest dollar on the style and bling in there before I'd do anything else to the house.

Sphinxface
if you remodeling to sell check out with your local real estate people and then evaluate how much you want to invest in the project. Bathrooms even small ones tend to get expensive and I believe it is about 75% return on you bathroom investment? OTOH if you sell you house much faster due to tastefully done bathroom...
There are beautiful acrylic and vinyl out there and there are tacky overpowering marbles. Everything in the eye of beholder and your particular location, financial situation and whole house detailing.

I agree on some things with igloochic, but not on others...the thing I agree on is that it *all* depends what your neighborhood competition is. I'd base a lot of decisions on what houses that are selling well in your area have in them. Research first! Then you'll have a few real-life-based (as opposed to dream-bathroom based :)) choices in each area to consider. I prefer not to say things look "cheap" because there is such a thing as overbuilding, depending on the market, which is *never* a smart move. Wonderful places like G'web are notorious for leading folks to overbuild. So be smart and inform yourself on what the comparables are before you choose.

For example, re the tub: if you are planning to replace it, you don't necessarily need to upgrade to some sort of jet. There are plenty of folks who are putting in a nice deep soaking tub in many markets. We didn't put a whirlpool in our master, even though we could have, because I just didn't want one--I wanted a nice deep soaking tub that two of us could sit in from time to time, but not take up loads of water--we got a Maax Melodie. (Be sure to look at the min/max gallons for any tub you choose, and consider the capacity of your water heater!) The plan is to have a hot tub outside, and a simple soaking tub inside. To me, assuring comfort was the main point of the upgrade, so replacing a less-comfortable soaking tub with a more comfortable one would also be a smart choice.

Although if this is going to be for older folks, you don't want it *all* that deep, since folks have to be able to get into it. That's a whole 'nother set of questions, e.g.: does the house have another tub somewhere else? Would this area be a candidate for replacement of the tub with a more accessible walk-in shower? Those can be lovely and just as luxurious. But the general wisdom is that you need one tub somewhere in the house, so maybe this one has to stay.

Another aspect: tile is not necessarily a given, because what you are *able* to put on your floor is completely dependent on the strength of your subfloor. See the "deflectolator" or whatever it's called at the John Bridge Forum to find out if your subfloor can support porcelain or stone. We put porcelain tile on the ground floor, but are putting cushioned vinyl (fiberglass floor, either IVC Flexitec or Tarkett fiberfloor) on the second floor, because of how our house is built (not fabulously) and the fact that that bathroom up there isn't a high enough priority to me to bother with reinforcing joists just so we can have tile. There will be no seams in the flooring, which is one thing that really matters, and would speak against vinyl floor tiles from a practical point of view. Seams = water damage possibility. I'd really consider a higher grade sheet material instead of vinyl tiles. The lines I mentioned are very different from lower-grade vinyl, AND have the bonus of being DIY-install-able.

Shower walls: As far as I know, there's no reason not to do tile--it's not a matter of deflection like on the floor--although you might want to check this with Bill or mongo or the John Bridge Forum. Tile isn't all that hard-you just have to be careful with the preparation. Another alternative, more expensive but easier install, is solid-surface surrounds, e.g. Swanstone (lower end--but not that thin fiberglass stuff that cracks if you look at it) or Corian (higher end) or another kind of solid surface. You can get matching shelves for those too. You could install those yourselves too.

So the first assignment for you, which none of us can do, is to research your neighborhood comps and get details on what is considered a "value-add" and what is considered a liability in each area you're considering. Then, you can report back and we can help you winnow out the choices from there :)

(My, I'm feeling chatty today--gotta get up and do something!)

I've seen some very nice vinyl, but it has to be sheet vinyl. We have vinyl tiles in our upstairs bath...ugh, don't get me started.
We also have a fiberglass shower surround in that bath, and while it's not hideous, it certainly was not a draw when we bought the house :P
Ceramic tile is pretty cheap, especially if you are doing a tub/shower.