Your question is really vague, what have you come up with so far? A "good sized" shower means different things to different people? What measurement range do you want? You really need to provide more details, people here are more than happy to help, but they can't design a whole bathroom for you. At least post the drawings you've come up with so far, that will help the forum to see what direction you're trying to go in.

A small bathroom is a small bathroom, and unless you remodel your home so you can add to the bathroom's space, that's going to be the news. But from that, it does not follow that you're simply stuck with an inadequate bathroom. Replacing worn-out sinks and vanities will surely help, but if all you're doing is more of the same, that's what you'll be left with--more of the same. I would very much recommend buying the very best your budget will allow and searching the Internet for innovative ideas. You will be in the bathroom every day of your life. Why not make that place a true retreat? With a little imagination, you can. Here is a link that might be useful: Cabinet & Furniture Trends & Information

Linen needs to go somewhere. What kind of linen? If it is just towels they could go in the vanity drawers. But I'd take a linen closet over a makeup vanity any day :) You can have a top drawer for your makeup at the sink. But then I never spend more then a few minutes on makeup. I prefer to stand. I have never had the setup to sit down, who knows maybe I'd like it. Put all drawers in your sink vanity, or if there is a door at the sink, be sure to add pullouts some how. This way it will keep you organized and prevent you from having to crawl on the floor to get those lost things in the back of the vanity cupboard. Pocket door at the toilet area to recess into the wall on the left tub side. This will open up the toilet and allow access with if someone falls in the toilet room. The way you have it the door would not open. If you want to know how I know this let me know. Can be a frightful situation. Sometimes people go to the toilet when they aren't feeling well and passing out with the door closed could be disastrous. Anyway pocket door on that small room would be perfect. Looks like you have a window next to the toilet. I know several people who love their windows next to the toilet. Gives them something to look at. My carpenter built his home with his toilet across from a window for this the view. When I planned my shower I made sure there was access to the rough-ins from the back side of the shower. Can you do that? Dry wall would be an easy fix compared to ripping out tile and fixing. I don't know much about exhaust fans, but I put 2 in my remodel that joined in the attic to exit the roof as one. My bathroom is 8.5'x 10'. I love the 2 exhaust vents, one at the shower and the other by the toilet. There are lights within each vent as well. Electric, where will your switches go? You have room near the vanity. What switches will you need? I have a heating light in the ceiling and floor heating. Both of these switches are at one side of my room along with a ceiling light. The other side of the room as another switch to the same ceiling light, a switch for my LED toe kick light, and last, the switch to the exhaust fan. My vanity light is at my vanity along with some outlets. I also put outlets in my vanity to hold my hair dryer. You could put an outlet in your linen closet too if needed. Put an outlet by the toilet in case you get one of those advanced toilet seats (which I love Btw). I have more electrical work in my bathroom for my stacked washer/dryer and ironing station. Just look at your layout carefully for switches and locations for outlets. The entry door to the bathroom takes up a lot of room too. the area at the latching side looks almost too small to accommodate switches and casework. If you put another pocket door to recess into the vanity wall, you could utilize that larger wall for switches. The tub may be cramping the vanity, but I am not to sure about tubs. It looks pretty wide at 4 feet. Is it really that wide? and do you need it that wide? Where will your Heating/AC enter the room? I put a toe kick heating vent in my vanity and am very happy with it. I added a bit of insulation on top of the kit to keep the vanity from getting hot (if I remember correctly, so many details. It could be that I didn't because it wouldn't fit the space).

As it's pictured, this is an awkward bathroom. I don't see a shower fitting into this corner -- I think you've gotta start from scratch and re-design this whole thing: - I never like toilet-in-a-closet designs; note that this one is about the same size as a public toilet stall -- those things aren't comfortable. The issue here is that when the toilet door is left open (which will be often), it blocks your main entrance to the bathroom. - The closet door in the center is preventing you from putting the shower on one side of the bathroom, which would be the most logical choice. My best stab at it -- and I don't think it's 'specially good: This does place the sink, the most-used item in the bathroom, immediately by the door. It tucks the toilet behind a wall, meaning it's hidden from view but it removes the problem of the conflicting doors and gives you more room for comfort. The shower is quite large, and the door is out of the way. And you're left with enough space for a wide linen closet adjacent to the shower. By moving the closet door a bit to the side, the shower fits in a more logical spot (more logical than the NE corner). Another thought -- simplify and reduce the space, allowing for a larger closet, yet you still have all the pieces you need: