That's funny, I find playing high level spell-casters starts to get kind of boring.
I can spend hours trying to optimize my spell selection so that any encounter I face can easily be defeated with one spell. I can spend hours scrying locations waiting for the perfect opportunity to strike. I can spend hours optimizing my magic items and making sure my party is buffed and ready to go. Or, I can just say "to hell with it" and have fun and make do with Fireball.
All of what you describe is a problem I call, "playing the game outside the game". Basically the stuff most significant to the group's success or failure come from things that are far removed from roleplaying, much less the tactical battlefield. Optimizing spells and magic items and buffs is stuff you can do at home, alone, with a set of rulebooks. (Or at the very most by emails between you and the DM asking about the results of your divinations.)
That's a terrible gaming experience when it happens. The most important part of a group's success or failure should not be happening away from the gaming table.