Generally, I like to preselect the magic items that will be available to the players in the game. And I make most of them readily usable by the characters. If a fighter prefers to use a halberd, odds are he will find a magic halberd instead of 10 different magic swords. It makes the game more fun for the players, and avoids the "every fighter uses a sword, since most magic weapons are swords" syndrome.
I do use some random stuff, though. It's not completely missing. Usually this is stuff like a miscellaneous item or a potion. If I just want a magic item as a treasure, but I already have my placed items decided, then I will roll, though on the potion, etc. table, instead of the main generic tables.
I know a lot of DMs aren't really into this, but I like doing it. And sometimes I can add in a cool item that would probably be impossible to get by random rolls.