I agree, interval training will definitely break up your week and keep it interesting for a sprinting runner. I run 4-5 times a week but do some form of cardio everyday. When I run, I run 4-6 miles a time (you can work up to that with no more than a 10% increase each week).
But basically, just to give you an example:
Sunday (long, easy run...run this even slower than you think is "comfortable", just a bit more than a jog really. The idea is to get comfortable running for that length of time. So, for these runs, I run for time, not distance. If your max milage is 3 miles right now, then aim to run easy for 30-35 minutes and increase it by 10% each week.) This gets your distance up.
Monday (bike, row, or swim...keeps up with cardio but gives your shins and IT bands a rest from the pounding)
Tuesday (interval training - you know what that is) This gets your timed run/pace up.
Wednesday (bike, row, or swim)
Thursday (Run at an uncomfortable pace - suck it up and do it as long as you can aiming for 2.0-2.5 miles, increasing pace by 10% each week) It's supposed to burn - this takes your interval training and applies it to your longer runs.
Friday (rest day for long run on Sunday)
Saturday (easy 2 mil run to keep things moving)
Sunday (slow, long run, but this time for 33-38 mins)
Eventually, your "slow long runs" will be much faster paced than you once thought was "uncomfortably slow" before and you will be running for longer distances, faster. Dare I might even say you will eventually get to love looking forward to the long, slow Sundays to clear your head.