Depending on how far north you want to go, could check out Huntersville or Mooresville. There are some nice hotels near the University area (think there is a Hilton at the lake), but it's growing a bit unsafe up there. I live on the far south side of town and don't trek up that way much, but I'm sure someone else will have some ideas for you. Best wishes!
There are lots of burglaries, home invasions, car break-ins, etc... in the University/Harris Rd. area. You can link to a map of incidents on the Charlotte Mecklenburg Police website. But that's the I-85 corridor - I don't think you'll be coming down that way.
I assume you'll be coming down I-77 - there are many hotels along the road - all the chains - Comfort Inn, Holiday Inn Express, Hampton, etc.... Mooresville/Huntersville/Davidson/Cornelius is where you want to search.
I just checked Hampton Inn Cornelius here on TA- good reviews. Just use good old TA and make a choice.
Several hotels right off of I-77 in Huntersville....Country Suites, Hawthorne Suites, Sleep Inn are in nice areas (lots of shopping and restaurants as well). University area is out of the way. I prefer Huntersville area over the Cornelius spot mentioned, but that's OK as well. Huntersville is about 5 minutes South of Cornelius.
Mooresville is a really nice area - we stay there two or three times a year. We like the Sleep Inn the best - its a really nice, quiet hotel just off exit 36. We've also stayed at the Hampton Inn and its pretty nice, too. From what we've seen, Mooresville seems a bit less expensive than the Huntersville/Cornelius area
Thanks for all the info!