Lots of folks are saying to invest in the book. I would get whitewater of the southern rockies. Whitewater of the Southern Rockies
Its the updated guidebook with a 5 star quality rating and difficulty by flow. Definitely a big help for a CO trip. If you want to splurge, get the old guidebook, colorado rivers and creeks too. Its got some great stories. Don't forget the CO gazetteer either.
First two weeks of June is prime and you will have tons of options. Key is to keep and eye on the flows and go with the flow. Its not unusual for a hot spell to get a few things uncomfortably high, or for a cold snap to shut down high elevation creeks. Watch flows and weather and adjust plans accordingly.
Durango and Crested Butte are two excellent hubs. Camp at Oh Be Joyful Campground (right at OBJ) and there will be boaters to hook up with for shuttles etc. CB has a coffee shop to get internet access if you need it. OBJ is a great run, and tons of fun. Durango has several classics as well.
I would shoot for the most quality runs you can, and figure out a way to hitch shuttle or hook up with other boaters. The new guidebook has a hitching likelihood (great feature in a guidebook), which could help. Colorado is a traveling boater destination in June, so you could potentially hook up with other crews looking for the same runs as well.
I wouldn't shy away from hooking up with folks from mountainbuzz to share shuttles with etc. I have taken many an out of town boater down the river, and CO boaters in general are friendly and willing to paddle with boaters from out of state. If you really need some shuttle help or a guide for a run you want to get, post on here and see what you get. Its rare for folks to offer to hook up with out of state boaters who aren't legit, but a quick conversation will weed out those not ready for prime time.
While you can get from any drainage to the next in a couple of hours, and colorado is relatively small, its a long drive (7ish hours) from durango to the front range, so plan your travels to optimize boating and traveling. I'd look at the drainages you want to hit, and plan your road legs with google prior to coming out.
Bring the drysuits and cold weather camping gear. While June is summer in CO, it gets cold camping at high elevation, and the high altitude creeks are generally super cold water. I paddled OBJ in june when it was snowing and my hands were almost frozen.
If I were going to do a trip, I'd spend 3-4 days in Durango (upper animas, 3rd gorge lime, 1st gorge lime), 3-4 days in CB (OBJ, daisy, upper east, slate), a couple of days in the ark valley / roaring fork valley (clear creek of the ark, lake creek, castle creek into slaughterhouse), and 3-4 days on the front range (bailey, blackrock, SSV, big thompson, joe wright / spencer heights). If you did them in this order, you wouldn't have any huge drives between drainages, but check flows to make sure that the order works.
Also, do some searches on the buzz to dig up some old info. Lots of good info on camping, runs, beta etc.
Another good resource is www.eddyflower.com
Its basically and online guidebook with run descriptions, pics, and flows links. Good to plan your trip, and good to check flows while traveling.
Have a great trip.