I get these quite regularly (Being a UK platinum) - would be curious to hear your experience if you took it up.

From my perspective I've never replied up as;
1 - I spend my time in Marriotts (~150nights/year), so if they are going to give me a Marriott timeshare presentation I expect them to put me up in a Marriott hotel, not a Crowne Plaza so I get all my perks
2 - I'm not interested in a timeshare in Malaga, would prefer one elsewhere in the world
3 - If they'd like to entice me with a few free points then I'd be tempted to attend, rather than a cheap car/hotel deal



I've got to admit though it does sound like a reasonable price if you can get some well priced flights.