somehow i find myself hosting 18 people (15 adults & 3 kids) for thanksgiving this year. i've roasted turkeys with success before, but never for that many people. i'm figuring roughly a pd/person (we're having a ton of sides and appetizers/snacks), so that leaves me with a dilemna. do i buy one giant 20-pd bird or should i get two smaller 10-pd. birds? if i get two smaller birds and roast them in the same oven, how, if at all, might it affect the cooking time? i have a double oven but i'd like to have the bottom one free to keep side dishes warm (all of these will be made ahead). or should i just plan to warm the dishes in the ovens for the 30 minutes the birds are resting?
TIA for the help. i defer to my fellow 'hounds vast expertise.