I love dogs - sounds like you have some happy family members.
Based upon all the reports and reviews out - I think you’ll be quite happy with Lion. Should be very painless, and will consume a couple hours. Sounds like the download was good for about 40 minutes, then another 40 or so minutes for your system to do the upgrade and settle down. But the features seem to be well worth the $29 price.
The fact that this upgrade is ‘free’ for any other Mac you happen to have, makes this even more attractive. Or, you could pay $150 to upgrade each of your PCs to the next OS when it comes out ...