Could consider a house rule that you can only use one daily attack power per combat - <snip>
I've found that I pretty much control combat length by 2 methods. 1 is limiting people to 20 seconds to decide what to do. If they don't, then they can delay and come back but I will go on.
The second and maybe more important method is by encounter design. Don't use individual monsters higher level than the party. Brutes can go up to level+2, everything else stays strictly equal level or under (and under is better for soldiers a lot of times). Use minions freely. If they simply get slaughtered every time then have them appear in waves or have terrain that lets them get up close to the party without being easy fodder. You can overlevel minions btw as long as its not TOO much.
Basically lots of weaker monsters is faster than a few strong ones. You can tweak this with experience but never throw in higher level soldiers, they take FOREVER to kill.
Tactics can help too. Don't be timid with monsters. They should generally come right to grips with the party and even provoke OAs to go after back rank PCs. This makes the fighters happy and it keeps the combats short.
I like the more low level monsters approach, but got a few questions.
Lower level monsters have a harder time hitting PC's which seems to make fights less challenging. How do you get around this? Controller/Leaders who give bonuses can work, but you don't necessarily have access to those every combat. I sometimes fix this by using the lower level monster blocks, but increasing their attack bonus, though I'm not sure how much this impacts the difficulty of the fight. Like couple sessions ago I used some level-2 skirmishers, but gave them +2 to attacks so they behaved like equal level skirmishers for offense.
Also using more monsters on the table increases DM activation time. With 6 people at the table, you may easily end up with 10-11 standard monsters, and regardless of how fast you are, it takes time to activate them. Isn't it better to have a low level elite or two (or a few high level brutes) in most encounters to keep the activation number low?