LLC, single member, taxed as sole prop. Simple inexpensive, does not require all the minutes, etc of a corp. can elect taxation as an S corp. (Affects self employment social security taxes). Can have one person own, or group and appoint manager either one of owners or third party. Lots of flexibility. My (wife's) wash is 4 SS plus 1 IBA. If I bought a second, I would make another LLC to own it, perhaps set up another LLC to own all the individual location LLCs.