Weeds,
Seam sealing a non PU coated silnylon tent has to be done with the tent set up and can take a full day to dry.
No brand using this type of silnylon (including Macpac, terra Nova ,Wilderness Equipment...) does it , at best they send you a tube of silicone "included" in the price. (nothing is free...)
Last year TT seam sealed over 700 tents at Nevada City ($30 USD), however that is a very small portion of the shelters sent out it really is not practical to offer that as a standard service.
(PU coating reduces tera strength and can pick up mold or become brittle or sticky)
Anyway, if you like the idea of having a Tarptent I could suggest a Double Rainbow and a Cloudburst 3.
The Double Rainbow is our star tent outselling several of the other models combined.
The Cloudburst 3 is a 3 person tent good enough for 3 adults but still light enough ,and with a compact footprint , for two, so if one of the kids does not come no big deal.
It could be, later on, a larger double for you and your wife. (1.5kg for two or three is not bad)
Not cheap , particularly now with the low dollar but they still , I think, offer good value for money considering weight/size/ease of use.
Note that the lightest types of tents use more and longer guylines to stand up, so as you go from a fully freestanding shelter (generally heavy) to the lightest it can get more difficult to set up on platforms.
franco@tarptent.com