I have a couple questions:    First for those of you that have used a clay bar, is it worth the time/effort ?? I've used Liquid Glass for years on my cars with out any prep cleaners/clay bars etc. and I'm very pleased with the results....Just lookin' for opinions.

Clay bar, yes absolutely.  Think of all the years of junk you have accumulated on the surface. Washing it won't remove the grit and contamiments that you pick up in driving.  Clay bar will strip it off and leave a smooth finish that you can then start improving by removing swirls, polishing then putting on your wax.  And it really doesn't take that long.  I do it twice a year, don't even think about the effort, which is well worth it.  And my original paint is 16 years old but most people think I've had it repainted.  I'm not a waxer, but I know what great results I've seen. For the engine, try Simple Green.  If really dirty, use the blue colored aviation stuff, really cuts grease and grime. If not  real bad,  the regular green colored Simple Green, and a  lot of scrubbing will work fine. Use some 00 or 000 grade steel wool on your shiny stuff under the hood, then a good chrome/SS cleaner like Mother's, etc., you'll be happy with the results.

I used "engine detailer" on mine and had excellent results...just follow instructions on label...came out great spray gets into al lthe nooks and crannies where u can't really reach with fingers or a rag, brush, etc.....leaves a nice sheen on hoses weatherstripping around wheel wells etc without the high-gloss armor-all sheen....

What brand of engine detailer do you use?  I can't find it at my local AutoZone.

Clay Bars work great and you will not believe the crap that is on and in your paint. But sure you get a soft clay, the harder ones are also harder to work with.  Mequier,s made a kit that includes the solvent required and a good clay that works great. I usually do not endourse a brand but this one worked great.

I suggest that if you have never used a clay bar on your car before, do it once, then run your hand over it with a baggie. Suspect you will still feel contaminents in the paint.  Second time should catch all the minor stuff left behind. Do the baggie test again, you should feel the difference. 

Well, here's my two cents for what it's worth as far as the interior and exterior is concerned. These are some things I learned from my father-in-law who does very high end restorations.
Definitely yes on the clay bar. I also use a resin glaze, then I use One Grand Blitz Wax. For any of the plastic and dash, I use plain old Pledge. Works great and doesn't do what Armour All does to the plastic. Restores it awesomely.

Here's some of the f-i-l's work so you don't think he's just a bondo slinger.

I was a little skeptical the first time I used the clay bar, but was definitely impressed after trying it!   Now I even use it on my acrylic top!   No swirl or scratch marks!   Wash the car with a mild car shampoo and chamois dry before using the clay bar.   Slick!!