I am going to make a few assumptions: First is that you hunt outside of teh big game troips and could use the optics then. Second is that, with children, a future trip would be less costly if you purchased a pair of optics todya and did not have to buy a second pair in 8 yeras.
Essentially, in 8 years, you'd have an out of pocket expense equal to $500-$1,000 for 2 pair of lesser binoculars when you could have spent the same money and gotten a gret pair first. The kids are only going to get more expensive.
As yourself: Do you beat up your equipmetn or treat it well? if you are hard on binoc, you may need a new pair regarless of cost in 8 years.
I have two pair of binoculars that I use regularly. The 8*32 Swarovskis are infinitaly better than teh 8*42 Nikon Monars. They were also $769 vs $250. Where I see teh gibbest difference is in low light or at extended distances. On a recent trip to Yellowstone, the swarovskis significnatly out performed teh nikon's at extended distances.
The Nikons are adequate and appear to be a step above what you have. I do not think you will be disappointed, but there are better options for your money.
That being said, a friend has a pair of Pentax that are basically indistinguishable to the Swarovskis at much less cost. They are bigger at 10*50 and 8*42, but no significnat difference in viewing. At least not $500 dollars worth.
I think that$400 - 600 is a good price point and it does not appear that you will be using them a significant amount of time.
Bearbasin.com has a pair of Pentax 8*43 SP for $529 I would strongly consider these. They are a mid point for price, will last a lifetime with care andyou will not be dissappointed. Pentax has also reintroduced the 10*42 WP. It is $349 at the above website. A little less quality, but still a great set of binoculars.
If you are not opposed to used equipement or refurbished equipment, this sight always has demo equipmetn at some pretty good prices.
http://www.24hourcampfire.com/ubbthreads/postlist.php?Cat=0&Board=UBB36
I hope this helps and is wht you were looking for. Sorry for the rambling.