Personally I would like:
1. Driveable car or other veichles.
2. More bigg factions like the brootherhood of steel.
3. Bigger setlements. It's been a long time in fallout since the war wouldn't man start building new towns?
4. Living trees.
5. Harold

More of a survival game

more radio music

There's already an ongoing official thread for Fallout 4 http://www.gamesas.com/bgsforums/index.php?showtopic=995631 so this is probably going to get closed/

Anyhow, I hope with Fallout 4 they make it an effort to improve on the things that made Fallout 1 and 2 great games and were lacking in Fallout 3: a well-rounded SPECIAL system, great storytelling and a vast improvement on dialogue, both in voice-actors and what they have to say.

Brotherhood of Steel x NCR war to be made canon.
Super Mutants OR Enclave NOT the center of the plot.
More choice & consequence
Multiple paths to complete a quest
Unique weapon/armor/item names, example: "Hei Gui" Chinese Stealth Suit.

Bonus points: Obsidian develop it.

Please keep such discussions in the http://www.gamesas.com/bgsforums/index.php?showtopic=995631