I'm planning on spending July and August of this year climbing in the US. What are people's recommendations for destinations that are the easiest to pick up climbing partners if one is travelling alone? An area that offers multipitch trad routes would be a bonus, as would any destinations in Colorado although I would be willing to travel as far as Canada or Mexico.
For multi-pitch trad, in July and August, with a plenitude of partners available, Squamish is by far the best choice.
There are many other places with good summer trad climbing, but none of them offer the sort of lively campground scene and easy partner-finding that Squamish has.
Weather is usually pretty good in July and August, although rainy spells do happen. With two months, though, you'll be fine for waiting out the occasional 3-day rainy spell.
The Estes Park Valley, with Lumpy Ridge multi-pitch gear climbs, alpine "day" routes in RMNP, a strong MP partner-finder population of climbers. Routes 5.6 to 5.11, grade II to IV, predicable weather (occasional afternoon thunderstorms).