Citrus Shrimp Salad

I have a bunch of citrus fruit and lettuce in the house, and I saw some gorgeous big ol' shrimp at the store, and it's 80 degrees outside (woo!) so I am in the mood for something light, fresh, and summery. Cue citrus shrimp salad.

One orange - zested and juiced
One lime - zested and juiced
One lemon - zested and juiced
1/2 grapefruit's worth of supremed segments
1/2 of an avocado - cubed or thinly sliced
1-2 garlic cloves - minced or pressed
1 green onion, thinly sliced
lettuce - either butter or romaine
6 shrimp because that's how many I have - cleaned
Vinaigrette:
orange muscat vinegar from TJ's because it's in the cabinet and will go wonderfully, though you can use red wine vinegar, or more citrus juice for the acid in the dressing
olive oil
salt & pepper

Combine the juices and zests with a glug of olive oil (1-2 tablespoons worth). This is enough marinade for many more than just 6 shrimp, so by all means, add more if you're cooking for more than just yourself. If it looks like way too much juice at this point, you can set some aside to use as the acid in your dressing and forgo the vinegar. Add the garlic and a little salt and pepper and stir to mix. Add the shrimp and allow to marinate at room temperature for 10-15 minutes while you prep the rest of the salad and heat a grill or grill pan.
Clean and cut/tear the lettuce into bite sized pieces. Slice the avocado & green onion, supreme the grapefruit, and add to the lettuce.
Make the vinaigrette.
Grill the shrimp over medium - probably about 3 minutes on each side until pink and cooked through. Toss the salad with the vinaigrette, reserving a couple of tablespoons. Top the salad with the shrimp and drizzle with the reserved dressing.