Try boiling down the first runnings if you haven't. You can get some nice caramel and melanoidin production that way. Say your first runoff yields 2g; boil that down to about 2 quarts, meanwhile collecting the rest of your sparge and getting it boiling, then combine the two before pitching hops.
As for sugar additions, they only need about 10m but if you put them in with those boiled first runnings, you'll get an even thicker caramel reduction. Careful though, sometimes it will make for a less fermentable wort, so account for that in your mash schedule, etc. Most of the beers that like some caramelization also don't mine 70-72% AA it seems.
Also note that you have to work out the math on the IBU's depending on when you add the sugar and increase the SG (decreasing the hop utilization.)