The biggest limiting factor with the large is the grate size. I've found that I really can't fit anything bigger than a 12lb packer brisket without more creative solutions. I can feed 20-25 pretty easily on my large, but to run a party for 40 I needed my BGE, kettle, and a buddies' ECB. If you're frequently entertaining 30+ I'd go for the XL and get a reducing ring for everyday use. Without it you're likely going to find that an XL is fuel inefficient for the small amount of food that two people will consume.
I do frequently entertain larger groups so I'm looking to add an XL.
Large BGE // 22.5" Weber OTS to OTG mod // Blue Thermapen // Maverick ET732 // DigiQ DX2