I stayed at the Tasia Maris last summer but it's an adult only I believe so it depends how old your son is.

It's a Thomson Gold unit.

However, there are a couple of others very close by which are Thomson units Tasia Maris Gardens and the other is the Sands. They may have the same walk in showers rather than over bath showers.

They are all a short walk from Nissi Beach (10 minutes or so) but the Sands is right on Sandy Bay beach.

My son is 27 so that it not a prob do you think it wld be easy to roll in a shower chair sometimes there is a lip that stops this thanks for your help

I don't recall there being a lip as such - but then again, I wasn't taking too much notice. What I do remember is that I found the lighting was a little poor in the bathroom.

The best thing you can do is to contact the tour operators of any of the units you are interested in and ask if they have a special needs section/department. Each tour operator should have one and they should be able to tell you of ease of access into the hotels, dining areas, pool etc as well as accessibility to the bathrooms.

If you are booking via a travel agent, they can make this contact for you. Ask them to do it in writing or confirm the details to you or the travel agent in writing before you make your reservation...
Each travel agent will have a "Gazeteer" - a bit like a telephone directory, which gives details of each hotel/complex in the resorts. On top of that there are files prepared on each accommodation unit by tour operator every year when the resort reps arrive at the start of the summer. They're called PIF's (property information files) and they count such things as ramps, steps at entrances etc as well as checking door and elevator widths for wheelchairs along with checking fire extinguishers and such things.
If you're making the booking yourself online, take a look at the Sitemap (usually found at the very bottom of the pages of the website) for their special needs or it may simply be referred to as their admin department. Contact them and ask for the details directly for units which meet your requirements. Some tour operators have an online form / live chat where you can ask the question of a live person by typing in your requests. You should be able to ask for a transcript or you can copy and paste it into a word document so you can keep it and take it with you when you travel.

Better to check out all the details first! You want to be able to enjoy your holiday, not make it into a living nightmare for a couple of weeks. Don't be pushed into booking something if you're not sure or you don't have the full details.

As I recall, there were ramps into the Tasia Maris but I can't recall how you got outside to the pool area (ie if there were ramps inside from the reception/bar to the outside lunchtime restaurant by the pool). There is a walk-in pool at one end at the Tasia Maris.

According to BHI, the Dome beach Hotel has 6 rooms designated as specifically for "physically impaired guests" (sic) but there are no images of these rooms. See for yourself here:- http://www.besthotelinfo.com/default.asp?m=hotel&id=00067&hotel=Dome_Beach_Hotel
Just click on the "rooms" tab and you will see them listed as a room type.