I am traveling to Tel Aviv in February. I am a world traveler and have traveled extensively but this is the first time in Israel. I will be doing a dead sea and Jerusalem tour. I have 2 additional days for tours. Tel Aviv? Should I spend a whole day with a guide there (I am a US woman traveling alone)? Is it worth it to go to Galilee? I want to see the beauty of Tel Aviv but I am also very interested in the Christian sites.

Any unusual customs or things that I should be aware of?

You can spend one day on Tel-Aviv (I posted info for you on another site, I believe) and take a one-day tour to the Galilee:
http://www.eggedtours.com/nazareth-t...-tour-240.html

You received a very good advice from mbgg. A day tour to Nazareth and around Tiberias lake will be very interesting.

In Tel Aviv you can take the tourist bus 100, for 1 hour commented tour.

Actually, I think the Galilee (Galil) is the beautiful area, and Tel Aviv is "just" a nice lively Mediterranean city. I wouldn't characterize it as beautiful

If you are interested in Christian historic and archaelogical sites, you might want the whole 2 days there--Tiberias and other historic sites around the Sea of Galilee (Kinneret Lake), Nazareth, Megiddo.

Are these the only days you have in Israel (2 for Jersualem/Dead Sea and 2 for Tel Aviv/Galilee?). Or do you have other whole or part days? It isn't hard to get around Tel Aviv alone, most people speak English, things are well marked, and if you have just a few hours there you can still see Jaffa and some other attractive areas of the city

I have a 1/2 day tour scheduled for Tel Aviv. A full day Jerusalem and a full day Galilee scheduled. That leaves 2 additional days. Is it worth it to do the Dead Sea in Feb.? Too cold to get in the water? We are staying in Tel Aviv the whole time.

I am not sure about evenings free. I will be there on business and don't know the social schedule yet.

What is in Jaffa?

My associate is now going to be with me after all so I won't be alone.

I just went and purchased Lonely Planet's guide book (sorry Fodor's!) to read about the area's you are all recommending.

The Dead Sea is worth doing anytime. You don't have to go into the water but you should see Massada, Ein Gedi nature reserve and Qumran.

There are interesting sites in Jaffa. The old quarter which has been rebuilt and has a lot artists shops, the old port (now being renovated), the flea market, etc; an interesting place to explore.

I suggest an additional day in Jerusalem.

I was swimming in the Dead Sea (on the Jordan side) two weeks ago in December-chilly but soooo much fun!

I agree with an additional day in Jerusalem, if possible.
Even if you take a day trip, there will probably be sites you've missed or would like to see in more detail

If you want to go to Jaffa,,you can walk about 20 minutes along the waterfront promenade from the southernmost beachfront hotel area of Tel Aviv--Beautiful views both coming and going. If you do decide to spend the rest of a day in Tel Aviv, you can walk around the Neve Zedek historic area which also has nice restaurants and boutiques (This is someplace your local business hosts might take you).
Another idea to go on your own is the Eretz Israel museum complex (at the north eastern end of the city) which has an interesting archaeological site as well as history, glass, and other museum galleries indoors and outdoors.

Two days seem a bit tight for all the sights you want to see; (just trying to point out the right perspective). Anyway, if your schedule permits I would suggest that you spend some time in the "older" section of Tel Aviv. Someone mentioned earlier Neve Zedek, that would also be in that older section. Additionally, I would recommend the "White City" area. If you are interested in architercure in general, or in Bauhaus in particular, you won't regret having spent your precious time on this. Check out this site: http://www.tel-aviv.gov.il/English/ . Also make sure you click on White-City at the bottom of the page.