The Plan and the Budget are very speculative without an Itinerary.
First, make a list of places you’d like to visit. Manila and Hong Kong were a given. My itinerary 20 years ago was Rome -> Naples -> Florence -> Padua -> Milan -> Rome. My biggest regret was not going to the Amalfi Coast, and I found Milan to be just another big city.
Second, check the dates of activities that you really want to do. When I’d stayed in Padua I’d done a day trip to Verona and visited the arena there. Since then I’ve always wanted to see an opera there. A quick search and dates for shows only ran from late June, and only for a couple of months. The definitive and signature show for the arena is Aida, so the itinerary was going to have to be arranged around a few select dates.
Initially we planned Rome -> Florence (2 night side trip to Cinque Terre and alternative to Amalfi Coast) -> Venice -> Verona -> Rome, doable in 10 or 11 days. A few things needed changing though. Jess really wanted to visit Pompeii though, I wanted to visit Amalfi Coast, the need for time in Rome to get over our jetlag, and the realisation we didn’t really have to go back to Rome to come home, but could fly back from anywhere.
So extending our trip we came to the following itinerary:
Rome -> Naples -> Amalfi Coast -> Florence -> Venice -> Verona -> Paris
All that was left was to save some money and wait for some airfare specials.