I'm not a fan of deserts either, mainly because the landscape is so empty and dull. I also dislike the typical late-game period when everything turns dark and depressing, why can't it stay bright and colourful the whole time?
GFAQs - Where anything is grounds for moderation, courtesy of selective wordplay. XBL: DDR Midian / PSN: MidianGTX
I have to agree that I like the fire, ice, and desert areas as it does make it seem like more of an adventure. I also think it's neat to be inside creature and escaping. And, maybe it's me, but I've always loved a good jailbreak/prison escape...it used to be damn near mandatory thing in a JRPG.
I'm not a huge fan of them putting a futuristic level at the end of the game in a normally fantasy(medieval) type world.
I'll also add a vote to sewers-usually because of all the levers and doors and other hassles you have to deal with-someone mentioned Xenogears and ToS as an example which are good ones. Sometimes they can be done right-they just don't need to be a twisting labyrinth.
The extreme environments provide contrast and serve to make the world feel larger than it is. Plus snow is just awesome, volcanic areas always have a sense of urgency to them, and deserts are an interesting source of exotic desperation.
Sewers.......why the hell are there always sewers? I don't want to play with the rats in a dank cesspool or create a path through the unnecessarily convoluted use of trash compactors. I don't want to see the light at the end of the tunnel, only for some grimer to fall off the ceiling and assault me. Not cool. Note to all future castle-makers: stop building secret sewer escape tunnels thank you please.