The wedding party will be fully outdoors, would recommend shoes that are easy to walk on dirt and gravel with. Bring a jacket as it might get chilly as the sun goes down.
Sacramento airport is the closest airport at ~1 hour by car
Placerville has a Best Western: https://www.bestwestern.com/en_US/book/hotel-rooms.05478.html?iata=00171880&ssob=BLBWI0004G&cid=BLBWI0004G:google:gmb:05478 Or you could stay at the Historic Cary House in Downtown Placerville: http://www.caryhousehotel.com/#/ Friends of Lena and Cole can camp on the property the evening of the party. If you would like to do this please bring camping stuff.
I would not rely on ubers to get home as they are not common in the area Hangtown Taxi is an option but may want to be arranged in advance: (530) 748-8294
Wine tasting at many of the nearby wineries is a fun Sunday activity South Lake Tahoe is only an hour drive away and is beautiful! Coloma, where gold was discovered, is only 30 minutes away with great hiking trails and river views.