I'm organizing a Napa/Sonoma trip for somewhere between the last week of February and the second week of March. Two of the couples have been there before, one has not. Any thoughts as to best week to visit?

If you're asking about weather, between the last week of February and the second week of March, there would be no significant difference on average, and it's impossible to predict what the actual weather would be during that 3-week span. It could be anything from 80s and sunny, to low 60s and raining.

so true, sf7307, so true..(did you just finish the watching the game ?)
My B'day is at the end of Feb and I can attest to both
warm sunny days and cold rainy days for that time of year up here.
Don't let that stop you. It's a wee bit less crowded
around here that time of year, so come and enjoy !

R5

I don't know about 80s. We can hardly get days that warm this summer. And 50s are more like it if its raining. However, this can be a beautiful time of the year. It's not Spring yet, the vines are still dormant but the mustard is in bloom and the flowering fruit trees put on a show.

It's a great time to visit. Napa has the Mustard Festival and in Sonoma there's the Wine Road Barrel Tastings:

http://www.mustardfestival.org/calendar.html

http://www.wineroad.com/annualevents/3

These events draw a lot of people on the weekends but the weekdays should be pretty quiet.

Even without the Mustard Festival, it's beautiful up here at that time of year. "Oh, the mustard blooms 'neath the vine, and the Valley is awash in green..." (to quote a local song). Come and enjoy!

Thanks for input, I'm looking more for activities and wineries being open and any releases during those weeks than weather - that's alway a gamble.
So the Mustard festival & Wine Road Barrel Tastings go throughout that time period (last week of Feb to second week of March)?
Are all the wineries open for tastings?
I know it's a long shot any time of year, but likely any chance of lunch at Mustards or dinner at French Laundry that time of year?

For French Laundry you'll have to dial the reservations line at 10am PST 2 months prior to your desired dining date. Just start dialing a little before 10 and repeatedly hit redial.

The wineries are only closed on Thanksgiving Day and Christmas Day.

went to french laundry last week.
my best advice to help you get a reservation there is to have your hotel concierge call for you, 60 days prior. it was a very memorable dining experience.

We got a 5:30 PM seating via Opentable on-line.
We requested it at 12:01 AM Pacific Time, 60 days in advance, from here in Sonoma County, CA. For dinner you
need a party of 4 - for lunch, they have one table for a party of two. Sadly, we had to cancel, yet I found it
a pretty easy way to get reservation there.

From the open table website:
"Exact Number of Tables Available ONLINE via OpenTable.com
* Two tables are available online via OpenTable.com for dinner service, one @ 5:30pm (party of 4) and one @ 9:15pm (party of 4).
* Two tables are also available online for lunch service, one at @ 11:00 am (party of 4) and one at 11:15 am (party of 2) on Friday, Saturday and Sunday only. The French Laundry does not offer lunch Monday - Thursday.
* If an online booker cancels one of these tables, then it will immediately become available again on OpenTable.com."

R5

Flagging for advertising.

Thank you mods !

R5