If you are going on a honeymoon straight after your wedding, opening wedding gifts when you return gives you something to look forward to. On the other hand, if you receive gifts in the post prior to the wedding it is worth opening them so as to let the sender know the gift has been received. If the gift was money (possibly towards a honeymoon fund) it is polite to send a card thanking the giver for the gift of money, this also puts their mind at ease knowing that it has been received safely. You could send thank you cards to your entire guest list to thank them for coming to your wedding and celebrating with you, but bear in mind this takes time and could be costly.
It’s also a nice touch to send a card, or even simply an email, to your venue and wedding suppliers to say thank you for their help during the lead up to the wedding, and the day itself. Furthermore, leaving a review/testimonial is an easy way to show your gratitude, is beneficial to the receiver and helps future couples when making their own planning decisions.