There really aren't a lot of options, just basic chain hotels. All of them are over $100 a night whenever you want to go, sometimes higher. Nothing special for the pool areas, just basic pools with some bars attached. We have been in almost all of them since we live here. Double tree suites, Crowne Plaza, Hilton Oceanfront or the Raddison suites are the best.
I'm not sure if you understand the geography here but you will be landing at MElbourne Airport a tiny airport in the middle of a small town which is next to a sears store. To get to a beachfront hotel: You will drive to US1 heading East and then you will go over Eau Gallie causeway to get to A1A where the beaches are and the beach hotels are.
To get to Disney you need to drive West - either taking 192 for 2 hours from the beach or from I-95 to the BEachline to I-4.
So your 2 destinations are in exactly opposite directions. There is no coastline between Melbourne and Kissimmee, just don't want you to be disappointed.
If you are looking for a resort pool experience there is the former Ron Jon resort up in Port Canaveral but it is more expensive.
Why not just drive the 90 minutes to orlando after your flight and get a night at the Nick hotel or Coco Key for a cool pool experience? Melbourne is not worth the time unless you have never seen a beach before. However, watch out for jellyfish - they are having babies right now and it isn't fun to be stung.
