Not sure why you are going to Flagstaff, but it is perfectly situated for an exploration of the wonders of Northern Arizona. We were there for four nights last summer and used it as our base for day trips. I can certainly understand Bella spending much of the summer there. Our trip last summer (4 nights at Wyndham Flagstaff, one night at The View hotel at Monument Valley, 2 nights at the Maswick Lodge at the South Rim, and 5 nights at Wyndham Sedona) was the best family vacation we've ever taken -- and we've taken some good ones.
It's not the newest resort, but our 2BR villa at Flagstaff was very spacious, had a lovely balcony and a nice gas fireplace. The community center/pool area is very nice, and if we didn't have a pool at home and a busy schedule, we would have spent more time there. The resort also shares some facilities at a nearby country club. We used the gym there (very nice) and ate dinner there (very good).
There are so many day trips available from Flagstaff that I'm reluctant to recommend one over the other...but I will. Go north about 2 1/2 hours to Lower Antelope Canyon, just east of Page, AZ. It's a Navajo Tribal Park ($8 admission per person) and you take a guided tour of the canyon. We used Ken's Tours, and they were great. The picture in my avatar is one of about 100 I took in this spectacular slot canyon. We went all over Northern Arizona including Grand Canyon and five nights in Sedona, but Lower Antelope Canyon was the highlight of our trip.
Flag is also a decent base for visiting the South Rim of Grand Canyon National Park. We actually stayed IN the park, but Flag would work well if you get up early.
If you have time, Sedona (and the Wyndham Sedona) is certainly worth an hour drive or a stay. Spectacular red-rock country and an artsy-hippie throwback town. The landscape is amazing (don't miss the Chapel of the Holy Cross, whether or not you are religious) and the people/ambiance are like out of a time warp!