Dear L.,
Out of the expected 70 guests, how many are adults and how many are children? If there will be a lot of babies, you will need a place where diapers can be changed and you can expect a lot fussing a crying so there should be a place where parents can take their kids to clam down. (Quiet room)
The excitement and celebration of baby’s first birthday is for the parents and close family and friends. Your baby will not remember a thing. Sounds like you may have a large family and/or extended family? Do you plan to cater this event or have a family potluck? If you have access to a church or lodge hall with a kitchen, that might be the most cost effective way to go. If you have unlimited funds there are a number of restaurants in the area that would welcome your party. Again it would depend on the adult to child ratio to determine the best location.
Blessings……