Traveling haifa to Jerusalem
 

I would like to travel from Jerusalem to Haifa and back in one day to see the B'hai Gardens as cheaply but quickly as possible. Suggestions please. Anything remarkable between the two cities that we should not miss. I am accompanying a friend who has never been there but I would appreciate something new in the last twenty years since I was last there.

Also any suggestions for nightlife in Jerusalem the week of October 15.

You have two choices:
1. Take the #940 direct bus from Jerusalem Central Bus Station to Haifa Hof Hacarmel station, then take a taxi to the Bahai Gardens (do not take any of the other bus lines - they are much slower).
2. Take the #480 bus to the Tel-Aviv Arlozorov terminal and take the train from the adjacent Savidor station to Haifa HaShmona station. From there take the #23 bus to either the shrine or the upper gardens.

Note that you can wander around by yourself in the Shrine and lower gardens during opening hours, but you must take a tour to see the upper gardens. All information is here:
http://www.ganbahai.org.il/en/

Bus schedules:
http://www.egged.co.il/Eng/
Train schedules:
http://www.rail.co.il/EN/Pages/HomePage.aspx

If you take public transportation, sites along the way like Caesarea or Zikhron Yaakov are not really practical. If you drove you'd have maximum flexibility but rental cars are expensive for a day.

You could use the train and bus combination option to see some places in Tel Aviv that are new to you like the Palmach Museums or strolling the port or Neve Zedek neighborhoods.

I would have rented a car but I can only go and return on Saturday and the car rental places are not open on Shabbat.

Do you know if it is possible to get a driver for a reasonable price?

Saturday ?? THERE IS NO BUS OR TRAIN SERVICE ON SATURDAY ! Your only option is to take a sherut (shared taxi) from Jerusalem to Tel-Aviv and then another sherut from Tel-Aviv to Haifa. They coast about the same as the bus and they run on Saturdays.

A "driver" aka a taxi is going to be very expensive for the day. You are either forced to travel by Sherut--as described by mbgg above or consider renting a car for 2 days!