Newer cars/Van have a lot more electronics using the battery, so my opinion is, if it's going to be longer than 2 weeks, I would disconnect the battery. You will loose your radios presets though.
Just starting the van isn't going to recharge the battery, so depending on how discharged the battery is will determine how long you need to run the engine. Keep in mind the discharging can be cumulative, so try not to let it get below 50% before getting back up to 90%. If you test the battery, after running the engine, give it about 20 minutes or so to remove the surface charge to get an accurate reading.
On my Wrangler, if I'm not going to use it for a week or so I connect the Battery Tender.
Here in AZ batteries don't last very long, so I do as much as I can to prolong them. Both my cars 2010, and 2011 have gone through the OEM batteries. Of course OEM batteries aren't usually the best.