How is asking for a small contribution to a honeymoon any less grabby than a gift list?
Asking for ANY gift up front is 'grabby' I think.
You should wait to be asked what you would like, and brief both parent in laws on this too - as some family guests may ask them instead. At that point its generally fine to say "well, we'd write like xxx experience on our honeymoon or some vouchers/money to use towards it."
Lots of people find cash trickier as it means the value of their gift is more up front and obvious; this can be especially hard for those who are having a tight year, etc but don't want to have to tell others about it.
The value of the gift does not have to match how much you think a B&G have spent on your place at the wedding. They invite yo because they want you there, not to recoup some of the wedding costs. What they choose to spend on their wedding it their choice and their responsibility.
thanks to those commending our choice of honeymoon
No idea about Grand Prix but Singapore itself is lovely. We visited for a week last Easter and loved it!
Re other people's weddings and gifts
I have an invitation in front of me at the moment, for May. It's in London which is quite a distance from here - but somewhere the B&G wanted to have it. They set their budget and have invited (small) numbers accordingly so that they can have the venues they want. They have paid for two nights hotel accommodation for their guests, transport to and from the venues for all guests and they have not included any reference to any gifts. DH did ask him, as he's his friend really, and he has said he'd rather people just gave money to a charity - he has been seriously ill (still has the serious illness in fact though it is currently managed for now on experimental drugs) and the suggested charity is linked to that, though he also said that he was happy for people to choose their own charity if they preferred. We will donate and will most likely buy him and his fiancé a nice bottle of something - DH knows him very well so knows what they'd both enjoy.
as for what did I/DH ask for
Initially nothing and certainly no mention on the invitations. We got married abroad 20 odd years ago, on our own - only mid 20s but had been together for 8 years but had no child at that point. We then had a large blessing and party back home for family and friends. People did ask us so we had a shortish list of ideas which both PILs had copies of too to make suggestions if anyone did ask - nothing specific, no links to certain brands/designs, no big dining services that have to be split so you risk not getting the full one, etc. Just vague - oh, some white towels, some champagne flutes, etc.