NBR: Critique my menu, please?!

NikCole

My FIL is coming to stay w/ us tomorrow, so we are having dinner at the house w/ us, FIL and his fiance, my parents and my bro and SIL. I'm doing a Mexican theme... here is the menu:

tequila-lime marinated steak and chicken for fajitas (w/ all the fixings- grilled peppers & onions, cheese, sour cream, guacamole, homemade salsa etc)

black bean, fresh corn and avocado salad

Mexican rice

homemade queso dip and tortilla chips (which can also go w/ the salsa and guac)

Corona and blackberry margaritas! 

Or instead of doing steak AND chicken fajitas, I was thinking of just doing chicken, then making a pan of beef enchiladas instead... just for another main dish option. WDYT?

Anyone have any ideas for a dessert that would go w/ the theme? I was thinking maybe a tres leche cake... but I've never made one, and don't even know what it tastes like. I can't think of any other "mexican" desserts. Maybe something w/ lime???