I like a good mix of music and silence/ambience in a game. Some of my favourite overal sound in a game are the
Metal Gear Solid and
Silent Hill series. It's good when there can be silence and only the use of sound effects and voices for awhile but music is used to amplify action and drama.
It really depends on the game a lot though, as well. Obviously for some you want music to be continuous throughout play areas -- usually action adventures and the sort. Think of how catchy those songs are from the first few
Mario games . . . .
The use of music, properly can do a lot to enhance or take away from a game.