York Beach, ME to San Francisco, CA, in a Hyundai Excel hatchback with everything we could possible fit jammed inside, the bikes strapped to the back! It was a long drive- around 50 hours driving time, 3400 miles, and we visited friends along the way. Basic breakdown was 6½ hours from York to Syracuse, NY, then another 7 hours to Sandusky, Ohio. Another 6½ hours to Louisville, KY. Two days from KY to Denver, then 2 more days to San Francisco. There are slightly shorter routes but that's how we went.
We visited relatives in Syracuse and Sundusky, going to Cedar Point while in Ohio. We stayed outside of Louisville with family and toured the area for a day. We hauled it to Denver for a visit, then over to Gunnison, CO to see my FIL. From there we did a loop down to the Silverton/Durango area, Mesa Verde, Telluride, and back to Gunnison (this loop isn't included in the driving time- this was vacation!).
I am seeing 6 or 7 driving days in each direction, so two weeks is not really enough time for this trip.
How about Canada? You could drive out through Buffalo to Niagara Falls, up through Toronto, over to Quebec, then back to MA through either VT or ME. Yahoomaps puts it at about 1450 miles/24 hours of driving time. You'd have plenty of time to hit amusement parks (Six Flags in western MA, can't think of the name of the one just south of Rochester, NY), investigate Niagara Falls, explore Canada, see Vermont (Stowe, Ben and Jerry's, Cabot Creamery). You'd even have time to make a loop down through the Finger Lakes towards Ithaca and check out the gorges and wineries. Just remember- everyone needs a passport to go to Canada!