hi gWn&jEf,
i guess traditionally, it would be good to have 2 VIP tables (i.e. one each for groom and bride parents). its abt a sense of celebration with your family members.
however, you'll need to evaluate if you have sufficient 'VIP ppl' (i.e. grandparents, siblings, siblings of parents) to fill up the seats at each VIP table. if there are still a number of empty seats at each VIP table after including the key ppl, i suggest tt you reduce the VIP table to one. get both in-laws and immediate family to sit together at one VIP table. afterall, they're the REAL VIPs...
conversely, if both your parents have too many siblings (incl their spouses), i suggest that u go for one VIP table. this will save you folks the political headache of leaving anyone out due to seating capacity constraints. if there are so many VIPs, then whats the diff of being a VIP for the day? unless u're classifying both parents as VVIP... hmm...
cheers!