Our Daily Bleg: How to Handicap a Multi-Race Challenge?

From a reader named Kevin O’Toole comes a bleg that needs input from people with experience in the realms of running, races, and maybe Olympic competition. (We tussled with Olympic medal counts here; and Justin Wolfers harnessed your collective wisdom when he ran the Stockholm Marathon.) Here’s Kevin’s story:

For the past few years, I’ve had some ongoing bets with friends at work (a supply-chain management company in Atlanta) around weight loss and fitness — just to stay in shape and keep it interesting. We’ve refined things based on the concept we liked at StickK.com (haven’t been there in a while, but I heard about it on Freakonomics).
Last fall we had a bet around a 5K race, which my team lost. We want an opportunity to redeem ourselves, and being the engineering types we are (you should see our 5MB college-football pool spreadsheet), we’ve decided to complicate things a little and do four races with two teams of two.
The races will be run in the following order: 10K, 1 mile, 5K, and half-marathon (at least 12 weeks after the 5K). This is a good mix of speed and endurance, with spacing to minimize risk of injury and optimize training.
The challenge is this: we don’t think we should pick the winner based on total time. We want to reward the speed runners if they can win big at those races and reward the distance runners if they can put in time on the long races. If you just go by time, then 30 seconds in the mile or 1 minute in the 5K won’t count as much as 90 seconds in the half-marathon (or, conversely, the distance runner would have an advantage there).
Both teams are a mix of running experience: Andrew (five marathons and many 5K’s and 10K’s) paired with David (one 5K and one 10K), versus Kevin (a few 10K’s and 5K’s, and two half-marathons) and Eric (four marathons and many 5K and 10K races).
We want all four times to count toward the total for each race and for the overall, but straight-up time puts the emphasis too heavily on the 10K and half-marathon. What do people think would be a good handicap system? Some point system with a points-per-second factor based on race length? Some combination of total time with a factor based on the length of the race?

Please help Kevin as best as you can. Send you own future blegs here.