I was awfully confused when I first bought this house. Its brick and tile, and I didnt think it would need a/c but it transpired that the west facing glass doors generate a ton of heat so I have a window unit (skinny style that you cant buy anymore) which is reverse cycle. I switch it off at night because I am not in tht room, and I don't use it at all in winter. Its not an inverter type and its very noisy but not as noisy as the mobile portable style of a/c.
My house is tiny, and its design, ceiling heights, window locations etc dont lend themselves to a split system. I also had a skinny unit in my bedroom. That died over a year ago, and last summer I found that I only needed a fan. Its a good fan, very quiet, gentle breeze, and does the job much better than I expected. I've had ceiling fans in other houses I have owned in the past and did not find them very useful except to move air around. Never felt cool with them. I imagine today's fan designs are an improvement on the old ones I had.
As others have mentioned, having a whirlybird on the roof to extract roof space heat would be a good idea and thats on my list of to-gets.
Cost of running the Window unit is quite high, but only for that period in summer where the temp is regularly over 40ºC and the a/c struggles to keep the temp at around 30-32º. My personal ideal temp is about 22º so that is what I have the unit set at, most of the time. Cost of running the window unit is far less than running a portable (I've done both). Will i replace the current unit with a split when it finally gives up the ghost? maybe. I'll br trialling a summer with just a fan and see how it goes.
This post has been a real ramble... well, Sunday morning and I've been awake since 2am... thats my excuse.