A 'decent' venue is a rather better description than merely a 'big' one.

Personally, I think the formal, purpose-built concert hall is the very worst place for our kind of music (though I'm sure Mr Cap's building is a very nice one). Fixed seating just isn't appropriate. Seating at tables and/or around the sides is much better. It even feels much more of a participative social occasion when entering such a room than prohibitive rows.

Town halls (Oxford/Guildford/Loughborough off the top of my head and church halls (St Lukes LSO or the converted Norwich Arts Centre) are excellent, as are many other arts or community centres (Bracknell, North Oxford and Crawley spring to mind). Apart from having the facilities (like food, a bar and dressing rooms), they are the antithesis of the dirty back room upstairs in the sleazy pub with a 'members only' notice on the door. The local community is thus encouraged to participate, not be scared off by what they perceive as weirdos.

The nightclub/cellar bar type of venue is also excellent. In London alone there is the Scala (a former cinema) where Bellowhead have staged two highly successful bashes at an entrance fee of under £10, the (sadly threatened) Spitz, Borderline and Bush Hall (a former snooker club).

I have no intention whatsoever of taking up challenges to organise myself. Done that a quarter of a century ago and found it's a thankless task and absolutely impossible to please everyone. I'll give advice on programming to anyone who seeks it, but no more.