We have two whippets and they are the most amazing dogs I have ever had. So different from any other breed I have owned. They are goofy, funny, vocal, warm and loving but a bit needy. I cannot tell you how much joy they have brought to our lives and how much our daughters adore them. We got them when our youngest was just a few years older than yours and it changed their lives and enriched them in so many ways. But yes, as someone else mentioned, your kids grow up and leave home, as ours have now done, as my DH and I are the ones taking care of them and doing all the walks. But we love it. We walk them, we chat and connect on our walks and on weekends we take them to the beach to run free.
We found ours need good exercise, so long walks, but to keep them really happy they also need to be able to run so an enclosed dog park areas or somewhere they can stretch their legs is vital in my opinion. They love to run and are amazing to watch when they set off at full speed. We get so many people stop to watch them 'play chase' and run pelt down the beach.
Their prey drive is mental too so we have to be careful with them off lead.
Anything small and furry they want to chase so excellent recall if you have them off lead is vital.
Once they got out of the puppy stages as long as they had their nice walks each day and a bit of a run they literally snooze all day so are not high maintenance at all. One other thing ours love company and don't really like being left alone and will look at you like you are abusing them if you try to leave them. So just be aware of this. It may need work and building them up for being left for longer amounts of time. We leave ours alone now and they will quite happily just sleep while we are out for a few hours but it took us time to get to this point. They just love their humans. They also need cosy sofas, big soft beds and blankets and ours want to be treated like royalty. We literally have to 'tuck them in' to their beds at night like children or they cry!! 😂But they are honestly the most wonderful family pets ever.
The puppy years are very hard work though, no matter what breed. You only have to look at some past threads on here to see the cries of help from people who have had one and forgot how hard work it is and how much time it takes to settle them, toilet train them and give them the time and energy they require so think long and hard before you take one on that you are committed to the job of raising it.
If you do go for it, you are in for an amazing time!!
Good Luck