Sounds like an obvious first question doesn't it, but you really need to ask it first. There is no point visiting a potential wedding venue, falling in love with the idea of getting married there and not being able to make your dreams happen because another bride and groom got there first. If you've already chosen your special date, then we suggest you telephone the wedding venue ahead of the visit and state you can only make that date, if they are already booked up then get back to the list and find another fantastic wedding venue.
This is fairly crucial, you don't want to book a wedding venue that have a seating area for 250 people if you're only inviting 60 to a sit down meal. In turn you also want to ensure your guests can sit comfortably without being crammed into a small venue, or even worse, being left to feel as if they're shoved in at the back, and can barely see the top table. Once you've got a rough idea of how many wedding guests are being invited, you need to make sure your chosen wedding venue suits your requirements. Request to see a sample seating plan, ask about whether they have round tables, maybe even ask to see photos of previous wedding meals and how the tables are laid out. This will give you a good indication of whether you can seat your wedding party and ensure everyone is happy.
Some couples prefer to have a small and intimate wedding ceremony, and then follow that with the mother of all parties in the evening. If this is your plan, be sure that the wedding venue can accommodate this. You don't want to have 200 evening guests descend on your wedding and find them all squeezed in, or unable to get to the bar. Again, the flip-side is that you don't want to find out your wedding venue has a separate dance floor and bar area that resembles a barn - the single easiest way to have zero-atmosphere at your wedding reception is to find the wedding DJ or band playing to a half empty hall, with your wedding guests sitting around the edges not mingling.
Depending on what your personal choice is, whether it's a grand Victorian house you've rented for the day, or the local church hall, ensure you set your budget and stick to it. Wedding venues sometimes offer set packages, which include a single price per head for their meal, wine, toast drink and evening buffet. All venues should provide you with a price list before you book anything, check if there is a cost for hiring the venue, on top of the consumables. Some venues charge less for Sunday - Thursday weddings, whilst Fridays and Saturdays are more popular wedding days and may cost more.