IMHO, the most enjoyable element of wine is Israel is the people, so I'm recommending wineries with people who are friendly and interesting to talk to.
In the Jerusalem area I would recommend the Katlav, Katamon, Agur, and Yaffo wineries.(Links to websites at the end.)
Katlav is located in Moshav Nes Harim, and the scenery is beautiful. Owner/winemaker Yossi Yitach is very friendly and his wines are marvelous.
The Katamon Winery is a very small operation run by Avital Goldner, who spends half his time as a Sofer Stam and the other half as a winemaker. Definitely worth visiting.
The Agur winery is in Moshav Agur and run by winemaker Shuki Yashuv. Shuk speaks excellent English and he makes some wonderful wine. If you visit Agur make sure you have plenty of time - Shuki likes to talk.
Yaffo Winery used to be located in Yaffo but now they are in the Judean Hills area. I particularly like their Carignan and Chardonnay.
Heading north, I would try to visit Saslove, Eyal, Tishbi, Bat Shlomo (if possible), and Tulip (website links at the end).
Saslove turned Kosher a few years ago and released their first Kosher wines this year; I hear they're quite good. Winemaker Roni Saslove is knowlegable, passionate, enthusiastic, and a native English speaker.
Eyal, located in Moshav Givat Nili, is a new winery for me, and I visited them during Pesach. The setting, the winemaker, and the wines were all very enjoyable. Eyal is one of a very few Kosher boutique wineries in the area.
The Tishbi Winery in Binyamina is Israel's 5th largest (I think), but they still maintain a friendly atmosphere. Tishbi also has a really pleasant dairy restaurant, which is a great place for breakfast. They have recently added a Valrhona chocolate center to add a little variety to the visit.
The Bat Shlomo winery is new on the scene and I don't know if they're open for regular visits. I've been in touch with them and plan to visit as soon as I have a chance, so you might see a posting about them on my blog in the next month or so. At the moment Bat Shlomo has only a Sauvignon Blanc, but I understand they will be bottling some new wines soon (a Chardonnay and a Rosé I think), so those might be available by the time you get here.
Tulip is a rather unique winery, located in the special needs community of Kfar Tikva. The winery employs some of the residents of the community making the purchase of their wine something of a Mitzva (more about this on their website). Tulip makes quite a range of wines (I particularly like their Cabernet Franc) and they have a nice visitor's center.
It's a good idea to check the websites of the wineries to see when they're open for visits. For most of the small wineries it's always best to call first.
Here are links to the wineries' websites:
Bat Shlomo: http://www.batshlomo.com/
Katamon has no website, but they do have a Facebook page in Hebrew: https://www.facebook.com/pages/Katamon-Winery/135796016461804
Same for Eyal: https://www.facebook.com/eyal.winery
You can find all of these wineries on my Google map of wineries in Israel ([url]yossiswinemap.notlong.com[/url]) or Yossie's Google map of Kosher wineries in Israel (https://maps.google.com/maps/ms?msid=216077309031719733434.0004b75c578cf2f58580e&msa=0
I have also written about some of these wineries on my blog (http://yossiswinepage.wordpress.com/
Feel free to contact me if you have any questions: ydwine1[at]gmail[dot]com
Have a great visit.