Some favorite dinner party dishes, slanted slightly to the pescetarian side:
Soup: This Provencal fish soup is lovely, as is a mushroom soup of the light broth variety.
Appetizer: Onion tart. Easy, popular, tasty. Or mushroom strudel (which can be a good main course for a less formal meal---just make one big one instead of little ones).
Salads: I'm a fan of fennel salads (with proscuitto, pomegranate, watercress, or supremed grapefruit/blood oranges---go nuts) or this chanterelle and frisee salad.
Main courses: Halibut is nice and filling, and fish cooks quickly, which is good for time-pressed party prep. Or just roast a chicken and some root veggies.
Desserts: Creme brulee with an herbal twist is nice, or the cake/pie of your choice. Or a cheese plate and dessert wine, if you're sick of cooking.