just caught this one, too! We went to Newburyport last year. FWIW, the town docks do not have showers and they are fairly popular so plan on getting there early on Friday or definitely make that telephone call to the harbormaster. Try to stay closer to the mouth of the river, rather than towards town due to the proximity of the whalewatching boats there, they are loud!
This is the side of the river you want to be on, though.
Not Your Average Joe's (seafood, American cuisine) and Agave (upscale mexican) are great restaurants, BTW.
report back, please!
and if you do come to Portsmouth way, please give a pm - we'd love to meet you Steve, if our schedules allow! Wentworth is on the expensive side, check out our marina, Badgers Island Marina near the Memorial Bridge, a VERY short walk into town and Portsmouth is GREAT!