Dinner party near Westwood
Depends what you consider "reasonable." With that size of a group, your options dwindle, short of taking over a restaurant. The place which first comes to mind is Wilshire but I do not know if that will meet your price point.
2454 Wilshire Boulevard, Santa Monica, CA 90404
Wilshire is one of the hot restaurants in Santa Monica these days and its patio is great, but it is very popular, still busy, and will command premium prices. I Cugini was hot a decade ago, but is all the way to the shore. The OP doesn't specify what "reasonable" prices mean, but there are a lot of big spaces on the westside that have a lot of room to fill these days, so a party of 75 has some bargaining position. How important is easy free parking? Full bar? Are you open to Chinese (Hop Li) or Persian grilled kebobs and stews (Shamshiri) or drinks with old-time meat'n'potatoes (Billingsley's)? I tried a weekday happy hour at the Daily Grill in Brentwood recently and they were aching for customers -- drinks were discounted and happy hour bar food was $3.95 and $2.95 for fairly big servings, especially their pot pie.