Chock to chock is probably better as that's the time you can log whereas the Hobbs meter runs as soon as the engine is switched on (or on some aircraft the master switch) so time doing checks before brakes off is dead time and it's better not to have any pressure to hurry things along. As to aircraft it is a personal preference thing however the PA28s have 4 seats and carry more so are a more practical prospect for touring once you've got your licence. I haven't been to either of the fields you mention but as a general rule I'd go for the less busy one for training - you will always take second place to an airliner.