OK - time to clear up some confusion here. 1st off, there is no such thing as a VTech version of the Wii. There is only one Wii, the VTech console is nothing like a real game console. We are a gaming family, we have 4 kids, ages 6 to 14. We have 4 DS Lite hand-held system, 3 older GameBoy Advance units that don't get any play any more, a Gamecube, two Wii's and a PS3. I know kids, and I know video games.
Skip the Vtech. Again, it isn't a real game system and your kids will quickly grow bored of it, as parents there is zero apeal to the VTech, and I doubt any of your kid's friends would be interested in the VTech either. It is most definitely NOT like the Wii, it is a cheap rip-off and can't come close to the fun the Wii provides.
From what you described, just go out and get the Wii. Your 3 year old is too young to play ANY game system at this point. Your older son and you (yes, parents can play games) will have a blast with the Wii. It is a great family game system with several games you can enjoy together as a family. Your 3 year old will probably enjoy watching and participating in the excitement.
Also, the Wii will play all Gamecube games, which is a bonus, not to mention you can purchase and download hundreds of classic Nintendo games from previous systems. Finally, there will not be a new Wii (or X-Box or PS3) for at least 2 years, probably longer. The costs associated with developing a real game console (not the knock-offs like the VTech) is staggering. Hundreds of millions of dollars in research and development. Sony, Microsoft and Nintendo have generally followed a 5 year cycle in order to sell enough systems and games to recoup the costs in developing the system. Anyone who tells you that a new Wii is coming out clearly doesn't know what they are talking about, so ignore them
So, don't sell your kids short, and plan on getting a system you will play with your kids. The Wii is great for the whole family, you'll have a blast with it.