Go through the motions of living in it. When we were shopping in 2005, both of those Sightseer models were on our short list, as well as Winnebago's Class C equivalents, the Minnie/Spirit 29B and 31C. We ended up choosing the Spirit 29B based on how livable it remained when traveling, and chose a C because we had the need for an extra sleeping area when traveling with a house full of younger guests.
I'm not sure that this applies as well to the Sightseer 29R, or the Minnie Winnie/Sundancer two-slide equivalent, because both of those put the range in the slide out, blocking some of the kitchen workspace when slides are in.
What we found to be the advantages of these two-slide floorpans, over the "suppressed" models was having the dining area overlooking the patio side rather than the sewer side of the RV, the opposed seating areas more sociable for larger groups, and the two slides created more "useful" space when open than the single large one, which opens a single floor area, leaving the bedroom more cramped.
The disadvantage of the bedroom slide is that you have to open it to get to the cabinets under the wardrobe, or to make use of the vanity/desk in the bedroom. This is an issue particularly if you regularly make overnight stops at places where you might not be able to open slideouts, e.g. truck stops, rest areas, parking lots.
In the end, it should be the decision of the cook and/or housekeeper, because the differences pretty much have to do with the house. As a motor vehicle, a driver's choice, the two have the same wheelbase on the same chassis and with about 14" difference in length, will just about drive the same.
Tom Test
Itasca Spirit 29B
