The vast - like 97% - of the activity for Rocky Mtn NP is on the Estes side and it takes - in light traffic - nearly an hour and a half to get from Grand Lake to Estes Park. And, in the summer, you VERY rarely see anything like light traffic!
Just accept the fact that you will have an ok, but not much better, place to stay.
As much as we love Estes and Rocky we will not be going back but, keep in mind, we lived there for 8 years and also been back several times. Rocky IS beautiful but has been hit hard with the pine beetle.