Mich, the Denali Princess Lodge is closer to the road into the park (named Denali) than McKinley is. The McKinley Princess Lodge is along the southern border of the park, with no direct access to the main road in the park. Therefore, the wildlife tour (or the "natural history" tour) would be best from Denali P. Lodge. McK P would be good for river rafting or jetboat rides, or perhaps a hike or bike ride (if available). You might still be likely to see some good wildlife there too, but I haven't been there so can't really say for sure. Check the Princess website or talk with your T.A. for excursion & activity choices - I think there will be a good variety.
Fairbanks in late July can be anywhere from 50 degrees F. to 90 degrees F. (Really!) Not likely to be actually cold, except perhaps at night if daytime temperatures are relatively low. The interior of Alaska has more temperature extremes than the coastal areas, by far - probably a lot like some parts of Australia! Best dress code - layers, layers, layers!
Have a great trip! I'm jealous!