Usually lots of planning (well not really planning, checking availablity/fares) goes into initial long haul flights, particularly for award bookings. Although these days, I seeldom book a long time in advance (a bit easier getting flights from SIN then from MEL), but when I have booked a long time in advance, I usually leave the finer details of hotels, ground transport etc, until the last month or so. I do spend a bit of time planning on what destinations to visit, but not a lot of planning into what to do at destinations, that's more a day to day thing when there. Hotel selection can be a bit more of a project, so to speak, but it is destination dependent (often less important in the big cities, such as New York, as I don't really spend much time in the hotel room, other than sleeping).
However, also had last minute holidays with planning entirely on the run, and sometimes these can be really enjoyable too. Ones that come to mind include at 3pm ticketing a booking for a 9 day trip to Europe departing 9am the next morning, and all I had planned and booked when I got on the plane was a flight into London, a flight back from Munich and two nights accommodation in London. Worked out the rest during the trip, making it up as I went along (and ended up taking in Sarajevo, coastal areas in Montenegro, an evening in Ljubljana and Munich itself). Sometimes planning on the fly has benefits, particularly for seeking the sunshine.
However, also had last minute holidays with planning entirely on the run, and sometimes these can be really enjoyable too. Ones that come to mind include at 3pm ticketing a booking for a 9 day trip to Europe departing 9am the next morning, and all I had planned and booked when I got on the plane was a flight into London, a flight back from Munich and two nights accommodation in London. Worked out the rest during the trip, making it up as I went along (and ended up taking in Sarajevo, coastal areas in Montenegro, an evening in Ljubljana and Munich itself). Sometimes planning on the fly has benefits, particularly for seeking the sunshine.
I am always keeping an eye out for info on places I have pencilled in and keeping notes so when I start the booking process around 12 months out I already have lots of ideas. Then the searching and comparing really starts, especially since we have always had a tight budget so I have had to work hard to get the best value for money without missing out on the many things we want to do.
