A good hotel but not as great as prices may suggest...
Hyatt used to be considered an higher quality brand, and their Grand Hyatt or Park Hyatt are supposed to be the upscale version of their hotels. This stay at the Manchester Grand Hyatt proved to be a disappointment for several reasons, though the hotel itself offers some nice features. 
Public areas: Great location on the harbor next to Seaport Village, a shopping area with dining and small shops primarily directed toward tourist traffic. There is a nice bookstore, some art galleries, food stands and candy stores, as well as a number of shops selling gift items, clothing, souvenirs, and toys). There is also a beautifully restored carousel and horse drawn carriage rides that take you around area. The lobby of the hotel is vast, and both times I stayed at this Hyatt, filled with conventioneers. There are a few dining options but not enough for the size of the hotel, possibly because they expect visitors to dine in nearby restaurants on the harbor. Bars and lounge areas were frequently filled with business guests and convention goers. Also nearby: Convention center, Gaslamp quarter several blocks away, and Horton Plaza Shopping Center, several blocks away. 
Dining: Lael's serves breakfast. Redfield's serves snack/quick fare. I have dining restrictions so found the menu to be very limited (hot wings, sliders, soup, salad, hot dogs, and sandwiches). Only one vegetarian option on the menu was a panini of mushroom, pepper, zucchini, hummus, and goat cheese for $14. 
Sallys is the full service restaurant; however, it is only accessible by exiting the back of the hotel to the harbor. It has a beautiful view and my friends said their food was good. All the menu items included seafood, chicken or beef. There was not a single vegetarian option on the menu. For a hotel that has more than 1600 rooms, this seems to be very limiting to guests that don't eat meat. 
Prices for entrees at Sallys start at $26 for a smoked chicken breast with spinach. Most entrees were $32 - $39. Appetizers, sides, run $8 - $16; Sushi $8 - $14 for rolls. Reservations suggested. Inside atmosphere is dark, romantic, and not very family oriented, although outside seating is available on the patio. The day we went the patio was closed (odd for a Saturday night when the hotel was full). 
Rooms: Standard business type hotel rooms included a flat paneled TV, desk, wifi for a fee, views of either the city or the harbor. Corner rooms have large windows along each side showing expansive views of the harbor but are smaller than other rooms. Regular size tubs, standard amenities, no robe in room even though I was told I was upgraded due to my Platinum status in Hyatt's loyalty program. The biggest problem I had was with the thin walls. The room next door had a child that was up all night crying, possibly because she was sick. This is understandable. I have been through it myself; however, Hyatt should spend some money on better insulating the rooms from noise. On checkout the clerk said that Hyatt had just started offering a quiet floor that guests can request; however, there is nothing on their website that shows this as an option. 
Service: Good service from reception and bell staff. Did not order room service. Restaurant service was good. 
Parking: In excess of $30 a night.
All in all a good convention hotel with standard Hyatt rooms. There is nothing really "grand" about the Grand Hyatt other than its size. It has a great location but probably overpriced for what it offers with rooms during my stay beginning at around $250 a night not including taxes and fees.