I just got to 93, easily my best effort. And I might have made it past that if it weren't for ants blocking for the last delivery boy. Let me share with you a few tips:

- Ice cannons at both the anthole and as close to the pie as possible are critical. You can't live without 'em. I had been doing two at each location, but this last game I went with just one each (both upgraded eventually to ice level 2) and they worked really well.

- Poison spray by the anthole will do some initial damage (not too effective past level 70, unfortunately) and seems to confuse the ants.

- Use snipers as much as possible, and try to space them so as to take advantage of their range. Also: more snipers = range bonus for all of them.

My config to get to level 93 was this: one poison level 2 and one ice level 2 right by the anthole, as centered as possible; four sniper level 3s spread through the middle part of the map; one ice level 2 and several sniper level 3s by the pie, basically as close to it as possible (and with the ice in the middle). I started at the hole and worked back to the pie area, and any spare money I had near the end was used to add a couple extra sniper level 3s to that area. When you get to only having one slice left and the ants have a lot of health, you need a ton of firepower (and the ice cannon for slowdown) right around the blanket so you can focus on keeping the dream alive.