If you not planning on sanding your vanities down, you have to wash them down with something like TSP cleaner and use de-glosser so everything can be primed (usually 2 coats) and painted.

Buy new vanities and avoid the mess and all that time you will spend doing this not to mention by the time you buy the doors, hardware, and everything else, you can buy a beautiful vanity with shaker doors and be done in 15 min installing them.

Good luck

I disagree with GN Builders but then I am no pro. The vanity does not need to sanded, or primed. Just wiped down and not even with TSP as long as you paint them with chalk paint and then apply wax afterward. I did it about 2 years ago. I can offer no help regarding the doors. In an effort to update mine I added molding to the existing doors before I painted the vanity and am pleased with the outcome.

Is Menard's in your area?

If, I just noticed that they have unfinished maple Shaker doors in a limited range of sizes in the store. I think you can also order them online from Menards and have them shipped.