One thing I thought 4th Ed got right was the way they handled spell durations... i.e. instead of 10 minutes/level and such, they typically had spells last for an encounter, or a day. This is how I think I'd categorize spell durations:
Concentration
1 round/level
Encounter
1 hour/level
Day
1 Day/level
Permanent
Would you find this easier and more practical for your games? For me keeping track of 1 minute/level or 10 minutes/level and so on and trying to figure out how much they spill over into the next encounter can be a nightmare. This approach would fix that, I would think... right now, we pretty much hand-wave 1 minute/level as 'for the duration of the encounter' and 10 minutes/level as the next 2-3 encounters, depending on what happens between them.