Having just done my second sea trail last week, I can share a few things I did wrong and things I did right. First I got a good surveyor and let him do his thing. He showed me the each discepancy he saw without my having to look over his shoulder. This allowed me to look at things that were important to me and think through how I would address some of those concerns while the surveyor did his thing.
What I did wrong was let the broker rush the sea trial a little bit. I was still looking over the genoa on the foredeck when the broker started rolling the thing in. I should have stopped him so I could participate using the furler, but I let it go. I did check with my surveyor to make sure he'd seen everything he'd wanted before heading back in. I only took a short stint at the helm, but did take time to do a couple of quick stops under power and then backed the boat a couple of times to get a feel for how the boat would behave near the dock.
The thing to remember is, its your sea trial so take the time you need to see what you need to see. If it takes a while it takes a while. Don't let the broker or owner rush you and do check with your surveyor to make sure he's content before you agree to head back in.
Have fun and Good Luck!
s/v Palmetto Moon
1991 Catalina 36