Probably asking for the impossible here! We currently have a baby and a 6 year old. We haven't had many holidays since our six year old came along due to covid (did have Greece booked when just us 3) but we always said we'd do a decent holiday to celebrate our 40th birthdays and significant wedding anniversary which all fall within a small time period in 2 year's time. This would be when our children are around 3 and 9.
We are doing bluestone this year, then next year a weekend in Italy just with our eldest so he experiences the whole plane/culture change which he'll love, then a week bucket and spade/toddler friendly job in Cornwall all of us.
For the "big" holiday in 2025/26 we are pretty open to any time of year, any destination. Some ideas we've had are:
cruise (don't think we can stretch to Disney prices)
Cape cod (may be too expensive)
Malaysia
Nashville/smoky mountains
Greek island
Budget is probably £5k ish. We did Thailand for our honeymoon, open to going again but also feels a shame to go back to the only Asian country we've already been to.
The other option is we do a week AI in the med as a family somewhere kid friendly then husband and me go away for a few days for our anniversary. This feels the best option for a 3 year old, but not fair for a potential 9 year old wanting an adventure and old enough to enjoy being abroad with us. Equally don't want to get in the habit of leaving youngest at home -feels most fair for both of them while she's a baby but not as she gets older which she'll be by then.
Any suggestions hints or tips welcome! For info - the large age gap was not a choice. Sorry for the stream of consciousness 
Thanks in advance