Last time we stayed at the Polynesian. We rented a refrigerator, a little dorm size one. We got it for free, because I needed it to store medication that had to be kept refrigerated. They didn't ask me for proof of the medication, but do be prepared to show it if asked.
Actually, this fridge was really small. There was a freezer unit that could hold maybe one frozen dinner. You'd have a hard time fitting in a 1/2 gallon of milk. We did use it mainly for the medicine. If I had to pay for it, I would consider a styrofoam cooler instead. They just have more room. But do be considerate of the hotel. Put something under it such as a garbage bag to catch any spills. A small microwave sounds like a great money saver, too. Also, the m/w can come in handy to dry clothes. I used it a few times to dry out underwear. Just don't put anything in there with metal and don't put anything in there nylon or it will melt. Supervise closely! However, it saved the day once when all the socks and underpants I'd washed out the night before weren't quite dry. My only other choice was to travel with dry, dirty underwear, or clean, damp underwear. What a choice!
This has nothing to do with this thread, but its a funny little story I'd like to share. We recently stayed at a Marriott. My 5-year old son had an accident. I tried washing out his underwear, then decided it wasn't worth the effort. I put the underwear (minus the poop) in a plastic bag and set it outside the door. Well, imagine my surprise when we came back to our room later the next day to find a valet bag hanging on our door with ds underpants in it--all nice and clean! Apparently I used the plastic bag the hotel provides you with for valet laundry service. I didn't fill out the charge ticket, but there was a bar code on it identifying it as belonging to our room. Also, imagine our surprise to find $5.50 added to our bill for laundry. I didn't see the charge until after we checked out so we ended up paying it. Moral of the story--always check your bill!