We went in April so it was still fairly mild- and too much snow for us to go to Kazbegi which is how we ended up in Guduari instead!
I would go in July, but I don’t mind the heat. Tbilisi is supposed to get particularly steamy in July/August, but I would book a hotel with a pool.
We were only there for a week. 3 nights in Tbilisi, then we hired a driver to take us to Guduari where we stayed overnight. When the driver picked us up the next morning, he took us to the Friendship Monument, Ananuri Complex, Mtskheta and the Chronicles of Georgia on the way back (that pretty much filled up a whole day). We then had another 3 nights in Tbilisi and spent one of those days on a day trip to the David Gareja Monastery (small local tour group).
There’s still a lot more I want to do in Tbilisi and so many other areas I want to go to. Ideally I’d spend about a month there, but that’s not happening!
Last year eating out was pretty cheap compared to the UK. I would have said around half to 2/3rds of what you would pay here, but I think prices have really skyrocketed in the UK over the past 12 months, and not sure if it’s been similar in Georgia. We ate very very well and often over accidentally ordered because a lot of dishes were really meant for sharing.
If you do go, make sure you go to Cha Cha Corner in Tbilisi. The guy who runs it is fabulous- he’ll pour you shots of different flavoured cha cha, tailored to what he thinks you’ll like. I don’t tend to like much hard alcohol but he had a cherry one and then a chocolate cha cha which were both divine. The owner is very proud that he only has 5 star reviews on google maps, and quite rightly so!