Any time on any of these Lanzarote forums I see a question about exchange rates/travellers cheques/banks I always advise people to take a Nationwide debit card and put their spending money in their account and use the card in restaurants and ATMs like you would at home. This way you avoid commission and get a better exchange rate with the added bonus that you're not carrying a large amount of cash or travellers cheques.
This advice is usually met with a lot of scepticism.
So here's the proof, my Nationwide bank statement for my recent 3 weeks in Playa Blanca.
04 July 2007 Restaurante Tipico Canari PLAYA BLANCA. 47.62EUR at 1.480 £32.17
06 July 2007 Lanis Grill Playa Blanca PLAYA BLANCA,. 69.04EUR at 1.478 £46.69
07 July 2007 Restaurante New Orleans YAIZA. 37.91EUR at 1.475 £25.70
09 July 2007 The Irish Anvil Pub YAIZA. 42.50EUR at 1.475 £28.81
10 July 2007 Cash P. Carmen-Los D PUERTO DEL CA. 70.00EUR at 1.478 £47.36
11 July 2007 Cash Desplazado PLAYA BLANCA. 110.00EUR at 1.474 £74.61
13 July 2007 Cash Desplazado CASAS DE LA D. 110.00EUR at 1.472 £74.71
14 July 2007 Cash Desplazado CASAS DE LA D. 70.00EUR at 1.473 £47.49
16 July 2007 Cash C.Canarias YAIZA. 90.00EUR at 1.473 £61.06
16 July 2007 Cash Playa Blanca PLAYA BLANCA. 110.00EUR at 1.473
Withdrawal date 15 July 2007 £74.63
16 July 2007 Strike Bowling Snack YAIZA. 30.00EUR at 1.474 £20.35
16 July 2007 Il Commendatore PLAYA BLANCA. 75.02EUR at 1.473 £50.90
17 July 2007 Cash Desplazado CASAS DE LA D. 110.00EUR at 1.477 £74.47
18 July 2007 Cash Desplazado PLAYA BLANCA. 110.00EUR at 1.483 £74.17
19 July 2007 Cash Desplazado PLAYA BLANCA. 110.00EUR at 1.486 £74.01
20 July 2007 Cash Desplazado PLAYA BLANCA. 140.00EUR at 1.482 £94.44
21 July 2007 Cash Desplazado CASAS DE LA D. 110.00EUR at 1.485 £74.05
23 July 2007 Cash Playa Blanca-Ya PLAYA BLANCA-. 50.00EUR at 1.485
Withdrawal date 22 July 2007 £33.66
23 July 2007 Cash Desplazado PLAYA BLANCA. 110.00EUR at 1.485
Withdrawal date 22 July 2007 £74.05