You know that hill work is a valuable training tool, but your legs, especially the quadriceps, get sore after hill sessions.
Here are two possible causes of an adverse reaction to hill training:
First, your sore quads may be due to a fair bit of downhill running in addition to the uphill climbs. Normally, uphill running doesn't present much of a problem, but if you run downhill, your quads experience a lot of stress and can be sore for days.
A second possibility is that you aren't doing the hill sessions often enough to realize a true training effect. This results in each session feeling like you're starting over again. Hence, the typical soreness associated with doing something new.
If either of these sounds like a factor, I recommend doing your hill workout twice a week. This will help you and your quads build up some resistance to the stress. Then, after a period of time (perhaps six weeks), you can drop hills from your program and concentrate on another type of training.
Another cause of sore muscles could be that you're putting extra effort into your hill workouts, hoping to get more out of them. If this is true, back off on the intensity, come down the hills more slowly (or find a more gradual route to the bottom) and adjust your workout so it doesn't produce any more stress than your other types of training.
Remember, it's virtually impossible to get in all the types of training that can benefit a runner at one time.
You'll get far better results if you concentrate on one or two types of quality workouts for a few weeks and then shift to another training approach.