If your husband is working in the downtown ATL area, you should look south of Gainesville or else his drive will be way too long. Based on what you said, I don't think you will be happy in Gainesville. (whatever you do, avoid Gainesville city schools; there are two districts here in town: Hall County schools and Gainesville City Schools. Hall County is better, but be aware that many schools are almost 100% Mexican and very low income. Check
www.GreatSchools.net for student demographic info)
Flowery Branch, Buford and other areas down that way would be good choices. I think those areas are more family oriented than Gainesville is. There is a large mall and shopping area in Buford called Mall of Georgia and Buford has Bogan park with playgrounds, walking trails, and an indoor pool and kiddie play area.
Our water bill here is about $36 per month for a family of 2 adults and two small children. I don't know about gas because we only have electric.
I don't know much about home daycares, but I think it would be a workable option for you to try. You might need additional homeowner's insurance and check your zoning and homeowner's association before you try to get started. (do they allow home based businesses?)
Suwanee has a greenway bike trail that might be nice (I've never been there). But be aware that Suwanee is in Gwinnett county, which is a lot more crowded than Hall. Gwinnett schools will be pretty diverse. (again, check the data for individual schools) Your commute to Brenau would be up 985 which wouldn't be bad at all on weekends.
Avoid Lilburn, Snellville, Stone Mountain (check the thread on here about "ghetto suburbs".