I think it is lovely for the children to have time with loving grandparents. Mine stayed with grandparents from a very young age and it was just home from home on both sides. They then went on to stay happily with friends, school visits etc. The saddest child that I came across was an 11yr old who was so apprehensive about the school residential that it was making her ill and this was all because her mother had never let her stay anywhere without her. Luckily she managed it and it did wonders for her self confidence, but it was all so unnecessary and her mother's fault that she was so worried.
If you know some dysfunctional men there is no need to think they are all the same. I adored my grandfather when I was a toddler and apparently was his shadow- luckily my parents didn't have to be glued to me at all times!
The children are gone in what seems a very short time, looking back, but you are on your own (hopefully) with your partner for decades after that and it makes sense to keep the relationship fresh with time alone, especially if you have family only too willing to have the children for a night, or weekend.
If you are rushed off to hospital it is nice to know that your children are happily with someone else. I remember when my brother was born and my mother was rushed off to hospital in the middle of the night, I woke up to find my aunt instead but was quite relaxed with that, having often stayed with her.
And my husband is not 'like a big toddler'! ( Quite probably because his parents had a relaxed attitude about him having close relationships with other adults when a child- much healthier IMO)
You only get men behaving like big toddlers if the parents didn't let them grow up!
Give them roots and give them wings. It is a gradual process and a weekend with grandparents is a great way to start.
Since it is your DD going away she obviously doesn't think that her mother needed to spend every minute with her until she was 7yrs!