I did the bath a lot too, when my son was 2-4 or so. He's not as into it now, for some reason.
My 2.5 year old does try to do some rest hour/quiet time on days that she doesn't nap. I take her up to her room, we read a story, and then I leave her with a stack of books and 1-2 other toys that she likes to play with. Usually a pegboard with lots of pegs, and a doll with some blankets or something like that. A friend of mine puts in a quiet cd and tells her daughter that when the music stops, then she can come back down. That sounds like a fabulous idea to me. We started this very very slowly, with maybe 5 minutes, then increasing the amount of time. It's a time I now really rely on. All my kids have rest hour right after lunch.
Is your older one into books on tape at all? I sometimes put a story in, and would strap the baby on my back, while I cooked dinner or something. He might be a little young still, but maybe not? Other toys that keep my kids entertained without much input from me are foam stickers, playdough, the play kitchen, trainset, any toys with lots of pieces, and the rice box (though I need to be in the same room for that one otherwise it becomes a mess!).
I'm a total introvert and if I don't get enough quiet, non-interacting time, I get very grumpy. I do talk about this with my kids and sometimes they can empathize and stay out of my hair even if it's just for a few minutes. I also learned that I have to ask DH to take the kids at various times. He doesn't usually offer but si always happy to do it, somehow it just doesn't cross his mind. So if he's going to the store, he takes at least one kid with him. When he plays basketball, he takes one of our older ones. When he goes to watch football with a friend, he brings the toddler along. All of these things really help and he's happy to do them, I just have to let him know I need that. All the best, I hope you get some recharging time. When they're so little it's SO hard to get that, good for you for seeking it out!