I too just loved creative mode when I found it out. Before free building (devcommands+debugmode+b) I was spawning mats with commands, and before that I was server hopping with pockets full of mats. It's so much more convenient with free mats and no workbenches - and flying, 'z'. I even used to build scaffolds I could climb on to get to the place so pieces would 'snap' correctly. Recently I also started to use the console command [removedrops] quite a lot, so I no longer have to run around and pick up everything that drops, and overshoots from inventory.

+1 for mod "Planbuild". For the terrain tools - but big praise firstly for the opportunity to copy my builds!! All those hours constructing and designing (and lotsa re-building...), I can now bring my house with me to new worlds. Planbuild gives you the option for just placing the whole building, or a 'blueprint' of your build, then you have to gather all the mats for it (there'll be a box to fill with a list of mats).

*edit; no need to run the mod except for when making and placing builds, after you can turn mod off and run the game vanilla.