A couple of general ideas -

Distance and time -

Since you mentioned late May to early August - it seems like you will have about 10 weeks of riding and a few days for travel on either end. 10 weeks is seventy days - if you allocate 6 riding days of 66 miles each per week - that's 400 miles per week. I like building in a day off for unexpected things - weather, repairs, visiting with folks I meet, hiking. Some people like to ride nearly every day. YMMV. But You can easily do a 4000 mile trip in the time frame you suggest.

I have found that giving myself an extra day at the beginning and end of a major tour makes for a much happier start and finish. Glitches do happen - and if your PhD involves some stats - you must realize that the probability increases with more people. If you give yourself a day at the beginning - then delayed flights, delayed luggage, upset stomachs, etc. are far easier to deal with. And if everything is hunky dory - you can just relax and chill before the start. Same goes for the end of the trip. Nothing spoils the last few days of a cross-country tour more than trying to play catch-up or hurry-up. An extra day or two really allows for a leisurely and fun ending.

Meet ups -

Meeting people along the way has a component similar to the paragraph above. If you have to get to Peoria by June 15th, it can really spoil June 10th thru 14th. Also, most folks tend to live in urban or suburban areas which are tougher to bike through. Except for Louisville (which is a tough enough nut for cyclists) I'd ask people to meet y'all at a nearby park - and I wouldn't let folks pin me down to a specific date, either. One time I was doing a tour for the ARC and a woman in Spokane complained that I was two days behind schedule - not considering that I had started on the Outer Banks. I was a touch sarcastic in my response to her.

For example - with your friends in Colorado you could suggest that they meet you in western Nebraska, Fort Robinson State Park is really nice - or maybe the Black Hills. It would only be a three or four hour drive for them, but a 200-mile detour for you.

PS - If you are considering biking to San Fran, remember that by late July the Western Express route across Utah and Nevada is really hot, remote, and with very few services. I love Nevada - I biked nearly every mile of pavement and a lot of dirt - but I would pick Glacier National Park over Nevada in late July every time.