Characters: My group has been using painted, and often customized, miniatures for characters for years. Monsters are a pretty even mix of painted metal and D&D plastic, and the collection has grown to the size where I usually have a good representation for what the party is facing.
Markers: With the advent of 4e we have been using the Alea tool magnets for conditions.
Terrain: After years of using the vinyl battlemat, I used dungeons tiles for a while. For the past few years I have been using Dwarven Forge pieces and Miniature Building Authority buildings. I'm planning on creating a gridded outdoor terrain board for wilderness encounters.
Other: One thing that has facilitated our using the 3D terrain, is having a finsihed basement dedicated to gaming. Our group built a custom gaming table with a recessed area for the minis. The table has built in shelves for all the terrain so its easy to quickly set up.
It has really been awesome using everything. Those rare occasions where we play elsewhere without the accessories it feels off. To paraphrase Ferris Bueller, it's so choice; if you have the means, we highly recommend it.
