I have not used their 35mm C-41, but their 120 C-41 is phenomenal quality at an excellent price. With 4x5 prints, I think it runs around $5. Most pro labs will charge you that much for development alone, not including any prints. They do the 120 out of Dwaynes, who have volumes to sustain good quality c-41 results. I bet most local pro labs receive so little film volume, they have problems keeping their minilab equipment and c-41 chemicals within specs. (not to mention E-6).
Unless these are super critical, once in a lifetime type shots, I think you will be fine using Walmart sendout in 35mm. They may send 35mm C-41 to one of the few remaining Fuji mass processing labs left, instead of Dwaynes though. In this case, the risk would be possible roller transport scratches.
Note: I know for a fact that they send all 35mm slide film, and all 120 and 220 C-41 and E-6 to Dwaynes, which is itself a pro lab, with top quality results.
You might also try Walgreens. Although a bit expensive, my local Walgreens still does in house work, and keeps their equipment and chems clean and fresh. My negs always turned our immaculate. However, when the bumped negs only up to like $5.50/roll, I began taking to Costso, which also has great quality and still gets good volumes to keep chems fresh. $1.50/roll there.