Derrick Reeves
First Post
I took a look at all the 1 minute/level spells (the "run and gun" list as Monte dubbed them), and have fixes for a few to present. I'm not touching Bull's Strength, etc. with a 10ft pole, just for the record 
Aid
I've always thought this was a lousy spell. It's not without its charm, but it's out-weighed by the need to heal (amongst other things). I'm inclined to suggest a 10 minutes/level duration, so that it can be left "up" for the better part of the day's hard-slog.
Bane, Bless, Doom, Entropic Shield, Magic Fang, Magic Weapon, Shillelagh
These seem like pretty straightforward low-level combat spells. I'd say that making the duration a flat 1 minute would keep the spell useful.
Enlarge and Reduce
I think these will work ok with a 1 minute duration; but I'd like to add "Improved" versions of them at a higher level with the 10 minutes/level duration (and possibly greater effects).
Improved Invisibility
This is an excessively potent spell, and knocking it down to 1 round/level would still leave it well worthwhile. At the time it turns up, this still leaves 7 rounds of sneak attack madness.
Mirror Image
I think 2 rounds/level will work fine here. That gives the full minute of protection when the spell first becomes available, but shouldn't get too silly at higher levels.
Protection from Chaos/Evil/Good/Law
I think a 1 minute flat duration will work out on this group of spells. 1 round/level leaves low level PCs with little use for the spell.
Spell Resistance
I hate this spell. I want to cut its duration down, but I'm afraid that would make it useless. On the other hand, raising its duration would make it far too good. Bah. I'm going out on a limb here, but I think 1 round/level will still work.
There's still a number of spells I haven't got any decent ideas for. Your input, as always, is invaluable.

Aid
I've always thought this was a lousy spell. It's not without its charm, but it's out-weighed by the need to heal (amongst other things). I'm inclined to suggest a 10 minutes/level duration, so that it can be left "up" for the better part of the day's hard-slog.
Bane, Bless, Doom, Entropic Shield, Magic Fang, Magic Weapon, Shillelagh
These seem like pretty straightforward low-level combat spells. I'd say that making the duration a flat 1 minute would keep the spell useful.
Enlarge and Reduce
I think these will work ok with a 1 minute duration; but I'd like to add "Improved" versions of them at a higher level with the 10 minutes/level duration (and possibly greater effects).
Improved Invisibility
This is an excessively potent spell, and knocking it down to 1 round/level would still leave it well worthwhile. At the time it turns up, this still leaves 7 rounds of sneak attack madness.
Mirror Image
I think 2 rounds/level will work fine here. That gives the full minute of protection when the spell first becomes available, but shouldn't get too silly at higher levels.
Protection from Chaos/Evil/Good/Law
I think a 1 minute flat duration will work out on this group of spells. 1 round/level leaves low level PCs with little use for the spell.
Spell Resistance
I hate this spell. I want to cut its duration down, but I'm afraid that would make it useless. On the other hand, raising its duration would make it far too good. Bah. I'm going out on a limb here, but I think 1 round/level will still work.
There's still a number of spells I haven't got any decent ideas for. Your input, as always, is invaluable.