Even the Super Nintendo version of Wario's Woods has far better graphics than the NES edition that's available on the Virtual Console (and in Animal Crossing for the GameCube, if you still have that classic lying around). But Nintendo could go the extra mile and redraw Wario's Woods in big, gorgeous sprites for WiiWare, give the music a little oomph past the power of 16 bit processing, and make sure the game supports widescreen, which would come in especially handy for multiplayer matches.
Wario's Woods already features quite a few game modes, ranging from a traditional series of puzzles to a progressive adventure with boss battles, time attack and 2-player. And while some puzzle games are better off a solitary experience, Wario's Woods truly shines in multiplayer. In fact, I can think of few better video game memories than the intense, madly-competitive sessions I had years ago on the Super NES version.
Online play is an absolute must, and Wario's Woods would be a great game for Nintendo to promote WiiSpeak with. I think I'd buy it just to yell at my friends as I mercilessly assaulted them with perfectly-arranged combos.
Puzzle games have changed and evolved over the years, expanding in gameplay modes and options to keep the experience fresh. It's ironic that Wario's Woods has received no such revisions yet remains one of the most fun, underappreciated puzzlers of all time. Just making the game available in its superior form, with online multiplayer, would be a boon to the genre.
If Nintendo decided to add some new modes, supporting the Wii remote alongside a classic control scheme, so much the better. Small additions also go a long way -- unlockable characters to replace Toad, various works of art of the Mushroom Kingdom to be won and used as backgrounds -- sure, we're not talking extras to the extent of Smash Bros. Brawl, but when you combine fun rewards with an already-addictive experience...
Well, let's just say that if Wario's Woods does get a remake, I may have trouble getting anything done.