1) Why not go sightseeing?
2) Why don't we go sightseeing?
1) Why not buy this dress?
2) Why don't you buy this dress?
Is there a small difference in meaning between 1) and 2)? Can it be so that the 1) is just a suggestion while the 2) is also a suggestion, but based on a bit of very mild criticism or annoyance (We have been here for three days already and haven't seen a thing! Why don't we go sightseeing? or You have tried five dresses already! Why don't you buy this dress?)
Or are 1) and 2) absolutely identical in meaning?
If I were a native speaker of English, I would never shut up. :-)
Pope of the Dictionary.com Forum