Ideas for a Sunday Brunch (wedding on ME island) for 70 people

We do tend to lean on stratas often because they go so well with meat and cheese or kale, mushroom cheese. We then serve a heartly platter of bacon- or just stand all that bacon up in a row of glasses and next to the glasses more glasses with stacks of gently pickled veg like green beans and asparagus. A frui bowl with zooped up yoghurt is nice too. Also like the idea of some quick breads and jams, some smoked meat and fish, good cheese platters too. The scrambled egg muffins also work nicely in that realm.

I can't imagine ever cooking for 70, but if I were to give advice, it would be to keep things simple and buy as many good quality products to supplement the one or two mains you do make. A savory breakfast bread pudding or strata, as others have mentioned, could be the star. You could serve it alongside yogurt (greek, jazzed up with honey, vanilla and or citrus) and granola, muffins, preserves, a seasonal fruit, fresh squeezed OJ, and a brunch cocktail.

Cheese blintz with blueberry sauce, bagels, lox, cream cheese etc.
Oven baked French toast with berries(will hold well), lobster salad in little cream puff shells..

We go to Bailey Island every summer and for our morning after Lobster dinner I usually make a Lobster strata..which I put together the night before...I make a lobster stock & reduce it them make the custard for the Strata with a combination of lobster stock, half & Half & eggs... I add chunks of lobster to torn hunks of chewy bread along with lemon zest, generous amounts of grated pecorino & parmegiano cheese + chopped scallions sauteed in butter... I let it sit over night then pour some melted butter over top & bake. Since May will also be RAMP season I think a ramp & lobster strata would be amazing and for non lobster eaters Local mushrooms should be popping up as well and if there are no non lobster eaters, local wild mushrooms + lobster + ramps you have the best of Maine in the spring!

May is pre -blueberry season but peak Rhubarb.. what about starwberry rhubarb turnovers or hand pies as a sweet component, you could round it all out with a couple of salads.

Maine has the most amazing root vegetables a warm beet & potato salad could work out well as a side and I'm pretty sure you'll be able to find foraged Watercress at the farmers market that woud make a lovely salad. In addition I'd also do an array of local goat cheeses w Honey & Jam.

And Sparkling wine + a Dash of Local Lavender Honey Mead+ strawberry puree will make an amzing brunch cocktail.

We're actually moving to Brunswick in May..so now you have the menu for my first May Maine brnuch :)

Lobsters and blueberries are all I think about when the word Maine appears. Maybe a lobster chowder to start? That would stretch the lobster. Or lobster rolls for appetizers with tiny rolls. Or lobsters for a main course with melted butter or mayonnaise if they are cold. Jane Grigson has a lobster chapter in "Good Things". For the blueberries-- I like them in bowls, but it sounds too simple, maybe a mixed fruit salad with blueberries. Fruit salad served in orange shells is pretty. Blueberry cake, blueberry tarts, blueberry pie, blueberry muffins ... I've never seen a fruit soup made with blueverries but should be possible. Blueverry parfait mixed with red berries and layered with yougrt or pastry cream or whipped cream. Maybe a cooked vegetable salad or kale salad that can be made ahead and won't wilt. Champagne or prosecco or home made ginger ale (I've done this, it's easy-- juiced limes, chopped ginger, sugar and seltzer). Have recipes for some of these if you want to msg me. May wedding in Maine sounds romantic and lovely-- congratulations!!

Lobster! Look online for lobster bread pudding. I had some a few days ago and it was fantastic and can be made ahead of time.

Do you have access to ore tan one oven?

Maine? Wedding? Brunch? Will the blueberries be in season? I would suggest an egg dish - strata or frittata - at room temperature, a fruit salad, a vegetable salad or two, various small baked goods, bacon and sausage, and interesting things to drink.
Good luck! I've done several large brunches in the past and this is my general formula.

Strata -- there are lots of options, from sweeter types (e.g. baked french toast) to savory ones with meat and/or veggies.

Do fritattas count? They can be made ahead and served room temperature.