I'd like to rule out sorbets, etc.
This recipe was a huge hit around here: Peaches Poached with Basil http://bit.ly/flrMP3
In my family we love to poach peaches in wine and then serve them over vanilla ice cream. Depending on how many people you are serving, find a nice, dry white wine and add about a cup or so of it to a simple syrup (1 part water to 1 part sugar). Halve and pit the peaches and chop them how you like. Bring the poaching liquid to a simmer and steep thyme or lemon verbena or basil in the liquid (as you like). Then add the peaches and poach to desired texture -- I personally like them to remain firm. You can then top yogurt, vanilla ice cream, etc. with these and perhaps a little lavender honey?
I made this with apples one year when I went to passover seder at my friends house. Apple/peach crumble. The crumble topping can be made without flour using matzo meal, nut flour, oats, butter, brown sugar. Honestly I make this without using a recipe it depends on how many you are feeding as to the proportions, You could do one large or make in individual ramekins.
Thank you! What a gorgeous idea.
Last year, a friend of mine wowed her family (well actually, her husband's family and an even tougher audience) with Brandied Peach Compote Cake. The recipe can be found at epicurious under Passover desserts. Good luck!
You could also do a simple peach sorbet...or a peach semifreddo (I usually bring a white chocolate semifreddo which my mom supplements with a variety of sorbets).
After what is usually a long and filling meal, anything with fresh fruit is always welcome.