Upvote:3
If you are eligible for the Visa Waiver Program, and you do not plan on spending more than 90 days at a time in the US, then there is very little reason not to use the VWP. The cost of the required ESTAs is usually lower and there is less paperwork. If in the future you decide you want to spend more than 90 days you can always apply for another visa then.
The expiry date of a US visa is the last day on which you can enter the US. Having entered you can stay for as long as the admitting officer gives you, even if your visa expires during that time.
Also, theoretically, there is nothing to stop you entering under the VWP even if you hold a valid visa.