A few readers who are going to Bayreuth for the first time have emailed me to ask for advice, so here it is. My #1 tip for those who have tickets is - don't wait, book your accommodation now. Read on to find out why.
The nearest airport is Nuremberg, from which the train to Bayreuth takes about an hour and a half (with one change). However UK flights aren't frequent, so you may prefer to fly in to Munich (33/4 hours by rail, two changes) or Dresden (33/4 hours, one change).
Find best flight times and prices on Skyscanner.net. In summer, air fares do not go down if you wait, so book as soon as you can to secure the best price.
Rail times can be investigated on Bahn.de, where you can also buy your rail ticket. As in the UK, it's cheaper to buy in advance. However if you're travelling from Munich, Nuremberg or anywhere else in Bavaria (especially in a group) it can cost even less to buy a 'Bayern-Ticket', which is a sort of regional day ticket. German trains are generally crowded so I strongly recommend getting a seat reservation. On the same note, if you can afford first class, it's worth the extra for the space.
Alternatively, if you've got a couple of days spare and you really, really like trains, you could make the entire journey from the UK by rail (see Seat61.c0m for details).
If you can drive to Bayreuth (or hire a car once you're there), then do - it will give you far more accommodation and activity options.
Performances usually start at 4pm - bear this in mind in your travel planning. Also bear in mind that, contrary to myth, German trains do not run like clockwork. Deutsche Bahn is exceptionally unreliable (my experience is 50% disaster on longer trips), so it's wise to add a couple of hours leeway into your schedule. Basically, you will need to fly out at the crack of dawn to have a decent chance of attending a performance on the same day.
Bayreuth is a small town in a relatively remote area which doesn't get a lot of visitors outside Festival time. This means prices are high, accommodation is in short supply, and you should book a room as soon as you can.
The best hotel in town is the Goldener Anker, which you can only book direct. Rooms start at around €200 at Festival time. For other hotels, check out a price comparison site like Kayak.com, or, for ease of use, a booking site like Booking.com. Expect to pay €150 a night and up. Check out reviews on Tripadvisor.com.
Before you book, be careful to check the hotel's exact location; some 'Bayreuth' hotels are actually several miles outside town. This isn't necessarily a problem; they may be linked by bus or train, and local taxis aren't ridiculously expensive. Hotels outside the town centre compensate for their inconvenience by charging significantly less - €50-100 or so.
At the Festival
The Festpielhaus is on the edge of town. You can get there by taxi, local bus or on on foot, and there's a large car park if you drive. It's around 10 minutes walk from the railway station and 20 minutes from the town centre.
The dress code is formal, similar to Glyndebourne. Men wear black tie (or an artistic version thereof) and women either evening wear or smart suits/dresses. A Bavarian summer encompasses tropical heat, polar chill and varying quantities of rain, so bear in mind when packing.
Although performances don't start until 4pm, most people get there an hour or so earlier. There are also one-hour breaks between acts. This leaves plenty of time for eating and drinking. The formal dining needs to be booked in advance. There's also a self-service cafeteria, a popular sausage stand and several bars. Many people prefer to dine after the performance; several Bayreuth restaurants remain open late.
There's not a great deal to do in Bayreuth - which is fortunate, as there's not much time to do it in. After lunch it's all getting ready, travelling and turning up. If you have a late breakfast, that leaves you maybe two or three hours to fill. Unfortunately the main tourist attractions - the Margravine Opera House and the Richard Wagner Museum - are closed for renovations. Unless you enjoy pottering around small-town shops and lurking in cafes, I would suggest this may be your ideal opportunity to finally polish off À la recherche du temps perdu.
For more local colour, check out my posts from the 2010 Bayreuth Festival.
More recommendations welcome.