Here's what I do and have:
At home I'm using a relatively short appliance extension cord to get from the outlet in my garage to just outside the garage door. This cord is a flat style and is most likely 10 or 12 gauge if I recall correctly. Then I have a 15amp to 30amp dogbone that connects it to my RV's shore cord.
This allows me to do virtually everything I'd like inside the RV except run the air conditioning (based on this thread I'm now tempted to test the air when nothing else is running). This keeps my batteries charged, I can run my fridge to chill it before trips, and I can even use the TT as my man cave to watch TV. I also plug our regular vacuum cleaner into one of the RV's outlets for post-trip clean up.
I have longer 12 gauge and 14 gauge extension cords for when I visit non-traditional camping locations like friend's driveways or behind a barn at a ranch. At those locations I'll also run the water heater, microwave, etc but watch out for doing more at once than the circuit can handle.
So at night or other times you don't need air conditioning, running off a regular outlet at a friend's house should be fine. Just try to pick a circuit that isn't shared with high-draw uses (like a space heater).
Also never try to connect to an outlet meant for an electric clothes dryer. Those are high-amp circuits, but they're also 240V.
