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A quick call to the Las Vegas Convention and Visitors Authority (LVCVA) verified what we already knew: The LVCVA's visitor statistics quoted in the original answer do indeed include conventioneers.
According to the 2007 Visitor Profile Survey, the reasons for visiting Las Vegas included vacation/pleasure (42%), visiting friends/relatives (13%), convention/corporate meeting (11%), with gambling/tournaments, a wedding, passing through, and a special event filling out the other 34%.
That roughly corresponds with the visitation figures for 2007: 39.2 million total, of which 6,209,253 (15.8%, or one out of 6.6 visitors) came to attend a convention. Thus, the vacation traffic is far greater than the convention traffic.
And all the numbers in the survey -- an average of 1.8 trips to Las Vegas in the preceding year, spending $108.87 per night on lodging, $254.49 for the trip on food and drink, $114.50 on shopping, $47.57 on shows, $8.31 on sightseeing, and $555.64 on gambling -- account for both visitors and conventioneers.