Keeping Mid-Season Practices Interesting

We struggle each year as we enter October to keep our 6 hours of practice each week interesting. By this time the weather is often turning rainy and cold, the kids can become distracted and bored, and the coaches can become complacent and locked into a routine. Here are some techniques we use to keep things fresh and interesting:

Jim and I usually alternate practice planning week to week. This has two benefits - it gives us a week off every other week and allows some natural variety to surface as we bring our own style to the week. While we have a consistent warm-up and start-of-practice routine we try to bring plenty of variety in other areas.
Introduce new plays for variety. Jim and I are conservative with our playbook - we probably run 20-40% fewer plays than the other coaches at our level in Sherwood, but we believe in focus and execution on a core set. Still, we bring new plays on as much for strategy and game options as we do to keep variety in our practices. By this time in the season most of the kids are settled in their primary offensive position and should be ready to take on new assignments.
Limited scrimmage with our Sherwood teams. This week we ran "thud" scrimmage against another team on Tuesday night where we spent about 30 minutes on defense. The first half was running their next opponent's defense against their offense to give some "best-on-best" game-time simulation that is hard to get with intra-squad scrimmage. In the second half they ran scout offense for us, allowing me to do some instructional work to prep for our Saturday opponent. We plan to turn the table tonight (Thursday) and have us on offense for 30 minutes.
Get creative with new drills and competitions. We scour the internet and literature for new drill ideas and bring new material in to keep the kids focused and address problem areas. This is where creative, engaged assistants can be a huge help - this week my linebacker coach ran a great new drill to help the linebackers learn how to fight off lead blocks in power off-tackle and sweep plays.
Get creative with conditioning. Conditioning is an important aspect of our practices, but I despise spending time on conditioning routines that don't teach football skills. Most nights we end with rapid tackling and hitting circuits to both reward the kids for hard work in practice (they love to hit!) and slide in conditioning in a way that doesn't feel like conditioning. Instead of running lines or gassers, run plays on air out 30-50 yards. We do this at the start of practice every day after dynamic warmups and this works the kids just as hard or harder than lines and the kids get used to running our plays while exhausted. We also have a coach throw to receivers on every play even when it isn't a pass play to get them used to running routes and staying engaged (we don't throw to receivers more than 3-4 times in a game).