Numbers: I would have thought that we would be safer with room for 30 to 40 or so, rather than 80+ - at Llanstock some attendees brought their campervans / caravans.
No smoking in YHAs: You can always go outside for a drag or take up snuff, as there in no rule against that!
Location: My vote goes for Beverley, as its reasonably central and its accessible from Europe.
Date: Certainly not in October to rival Llanstock but there is no reason to clash with other events in Jan/Feb/Mar either - so NOT 11/13 Jan Strawbear at Whittlesey, 25/27 Jan Ale & Song at Helmsley, 22/24 Feb Middlebar Singers Reunion at Sidmouth or (for me at least!) 1/3 Mar Morris Ring AGM at Newport and 15/17 Mar Bideford Folk Club at Boscastle YHA!

Sing John Ball and tell it to them all ...!
Alan