We're planning a trip to Prague this spring. Kids are old enough that they may enjoy a trip to Europe. So, the eternal question comes up - what lenses to bring. 1) 18-105 and 16+UWA - this seems like a no brainer, however I am not sure that I would need the extra reach, and may be able to get away with a smaller package. 2) 18-55 and 16+UWA - this would give me a far more compact package with little loss of convenience and IQ. Although in the 18-40mm range, I'd say 18-55 is perfectly capable of holding it's own against 18-105. 3) I could try & get a decent price on a used 20/2.8, which would give me 15mm with UWA. Every report I read says it's better than 16mm, the question is, is the increase in IQ worth the money (they seem to sell for well over $200), and is 15mm going to be wide enough ? 4) I could also shop around for a used 1650, again the reviews say it's not bad between 20-40mm and is a whole lot more compact than even 1855, so this would make for a very small trip package. Any ideas ?