Hello and welcome to the RTA forums !

With a week to do a loop from Grand Junction you certainly have time for a relaxing and enjoyable trip, but there is so much to see and do in the area. From Grand junction you have the Colorado National Monument nearby, where you could do the rim drive. If you are ending your trip back in Grand junction you could consider visiting Arches on the way back and take UT24 through Hanksville to Torrey [passing Capitol Reef NP] and then take scenic byway 12 to Bryce canyon. From Bryce head through Kanab to Page/Lake Powell and on to the south rim of the Grand canyon. Then from GC take 160/163 to Monument valley and 191 to Moab for Arches and possibly Canyonlands NP's. The route could be driven in 2 days at a push, so breaking it down into smaller sections and spending some time from the car sight seeing should give you chance to get a good overview of the area.

The weather will be what it will be when you travel and there is a chance you will see snow, particularly at higher elevations such as Bryce and the GC. All you can do is keep up to date with road and weather conditions as you go and if it's going to turn nasty, alter your plans to suit.