Interesting thread, and good for perspective review of expectations using timeshares and timeshare membership options. I've included my experience over the last six years of SVN, II trades and II Getaways. Hope it's helpful to the rest of you.
Starwood
Since 2005 I've visited SVN properties a total of 114 nights at an average nightly cost of $68.34. This does not include deed costs or other incidentals (such as the Maui nightly tax), but does include MFs, SVN membership fees, and property taxes. Even if I sold my Platinum SVN week now I would likely recoup all but ~$6,000 of my initial cost, thus increasing nightly rates by an additional $52.63 (not including lost opportunity costs, which I believe - as others do - is incidental). If true, then my actual cost was $120.94 per night for the 114 nights, which is the "right" price for me.
This includes 34 nights in Maui, 23 nights at Harborside, 17 nights at Kierland, 13 nights in Cancun, 13 nights at Desert Willow, 7 nights in Priceville and 7 nights at Mission Hills.
II Trades
Since 2005 I've reserved 154 nights via II at an average nightly cost of $90.34. This also does not include deed costs but does include MFs, II exchange fees and property taxes. (Note I haven't included II membership, and should add this to my spreadsheet, though it's an incidental cost). Of my non-SVN club weeks my total cost was ~$4,000 plus the special assessment for SVN which I don't believe I've included in my calculations (anyone remember what the second year cost was for SVR Falls?) but IIRC was about $600 per unit for the second year, totaling ~$5,200 cost, adding $33.77 per night. If true, then my actual cost was $124.11, which is good for me (note it's only slightly more expensive than my SVN week). I think it's feasible to make as good exchanges as I've done with less expensive weeks, as well.
This includes two weeks in a studio, three weeks in a 1-bed, four weeks in a premium 1-bed, 10 weeks in a 2-bed, and two weeks in a 3-bed unit. An additional week from 2011 is already paid for and deposited waiting for trade (plus two weeks from 2013, not included here). Most of the resorts traded to are in SVN and Marriott along with a a few others (such as the 3-bed ski weeks at Grand Timber Lodge). For reference, the "worst" timeshare was in January at The Villas at Polo Tower in Las Vegas, but I had two XYZ weeks there with an average nightly cost of just $24.14 per unit for that stay.
II Getaways
I've reserved nine weeks (63 nights) using II Getaways at an average cost of $66.17 per night. This includes three weeks at Westin Mission Hills, two weeks at Marriott Grand Chateau, and weeks at Marriott Desert Springs II, Marriott Timber Lodge (ski week!), Four Seasons Scottsdale (for only $227) and even Harborside at Atlantis.
I paid for II's Platinum membership for this year and hope to use at least one or two Getaways, for $50 discount each, plus a Platinum Escape week (which are ridiculously inexpensive). However, since the average cost per week has increased over the last six years, this isn't going to reduce my average Getaway weekly cost in any significant manner.