Four weeks is not very long so I suggest you head to Colorado in June. We spent 10 weeks exploring CO last summer and felt that that was just an overview. We plan to go back some year and see even more of the state. In June & July the weather was great. It is a beautiful state and there are a ton of opportunities to travel off road to ghost towns and old mining camps.
One of the things we discovered is that moving every week is tedious and we decided that we should change our MO to moving every two to four weeks, and preferably the latter. Take your time and enjoy your retirement.
