I, speaking for myself, would DIY the bathrooms. In fact my number 2 and 3 projects are to redo our 2 full baths (after insulating the basement).
But I am comfortable with basic HVAC, plumbing, and electrical. I would have to learn the shower water-proofing. My wife has gotten very good at designing rooms if she has a good guidance materials our last project was a kitchen she designed and I build. I build the cabinets from plywood, moved the plumbing and electrical, did all the tile work, installed the appliances, and on and on. So, all of those learned skills can transfer.
Can it be DIY'ed? Yes! Can you? Yes! How much will you have to learn? I don't know, "I've done a lot of projects in the past" doesn't say what kind of skills you have developed. Will it be cheaper to DIY? Yes, unless you make a major mistake have and to redo a lot of work. Will it be quicker than hiring a pro? Likely not, unless you have a lot more experience at take time off.