we have a 4x8' shower, with a 36" panel of floor to ceiling glass, that is ample. the narrower your shower is the closer the shower head will be to the front edge. so if you only have a 3' deep shower you'll likely need more than 3' of splash protection.

if you find you have cut it too close, the biggest source of water flying out of the shower is off your elbow when you are washing your hair. if you can train yourself not to have an elbow pointing to the opening you'll do better.

Sorry, couldn't find a pic, but nnigrt is a good example. We don't even have a "step" to get into the shower. Flooring runs right into shower. It's a very good size which as nn said is important - along with proper grading of flooring.

yes, our shower was a renovation so we needed a threshold.

This is called a spray panel and is pretty common. You did not specify the size of your shower, so I cannot comment as to how large of a panel you can/should go with.

I do not know where you live, but I would throw one word of caution with a spray panel. Showers with just spray panels are considerably more drafty. This is not an issue in warmer climates, but can be an issue to those in the northern regions. The hot air and steam from a good shower will move air currents around and bring cooler air into the shower. We have had customers insist on spray panels in June, and say they love them, but when February comes around they are shivering in their shower and asking how we can convert it to a conventional door and panel enclosure.

You can have a very open feeling shower enclosure by going with a frameless shower enclosure with no header and clamps for your glass to wall and glass to glass intersections. Best of luck with your new shower!

the shower is a remodel and so I am limited. Size is 36 wide by 48 deep (pretty small). It is located between an exterior wall on one side and tub on other. We live in Louisiana so mostly warm weather except for Jan and February. We were even going to leave the front open and have the side next to the tub only go up 4 1/2 ft to give it an open feel. Is that too small for open on two sides?

4.5 ‘ is too low you will have water everywhere I also agree a shower screen would work at the entry.