Good news: As with banquet halls, the everything-under-one-roof convenience of hotels is a huge draw. Pretty much everything is already in place, including catering, baking, staff, china, booze, and linens. At a hotel, you'll be able to negotiate better deals and extras, like a wedding-night suite, valet parking, an after-party room, and guest-room blocks. There's also the added bonus of no traveling on either end of the event. And superlative service is to be expected: Hotels are used to large events and have dealt with every problem in the book, so glitches are guaranteed to be minimal.
Bad news: For better or for worse, you're stuck with the hotel's décor, which may include busy carpets or garish wallpaper. Hiring your favorite überhip florist or lighting designer may help the situation—but beware of hotels that have exclusive vendors. If you're a hard-core foodie, be similarly wary of set menus, as many hotel catering staffs are loath to break the mold (a liquor license will also mean a heftier open-bar bill). Hotels with multiple ballrooms are not ideal for wedding-factory-phobes whose worst nightmare is running into another bride (ditto having random hotel guests crash the festivities).