I've got a Chariot for my twins. If you want a dual purpose trailer-jogger, this is the one you want. Takes about 30 seconds to convert: you just snap out the hitch arm and snap in the front wheel. It's getting a little tight for the two of them now that they're 4, but when they were babies then toddlers, we logged many miles. Including half a dozen 5 and 10K races.

It's a bit spendy, but worth it if you use it.