Hi jln26. You're going to get a lot of opinions with these questions, particularly on the matter of combination blades, with part plain edge and part serrated.
First off, I think you're right in that the tanto point is not as useful as some other points. Excellent for penetration when stabbing, but not designed for careful, fine cutting. Also, CRKT tantos are chisel cut, meaning only one side of the blade is sharpened. CRKT also puts the serrations on the wrong side of the blade for right-handed people, in almost all their knives. I believe they put the edge on the correct side in the Stiff KISS, but can't think of any others. Makes cutting in a straight line somewhat difficult. People who are expert sharpeners often put a new edge bevel on the other side of the blade, and believe it works much better for them. I am too ignorant of how one does this to try to advise you.
Yes, the spear point is more flexible and utilitarian. Depending upon the point, spear points may be useful for stabbing, but often are not.
The matter of serrations is more difficult. Some people love serrations. Others do not care so much for them. Most are in agreement that for cutting difficult objects, such as PVC pipe, or hose, or many other tough to cut items, it is best to have serrations to do these difficult jobs. Or, at least get them started. Many people feel that a combination (combo) edge gives you the advantage of both types of edge. Others feel that the sections are so short, that they don't provide enough of either kind of edge to be most useful. This ends up being a very personal issue.
Because the points of serrations get the brunt of the duty, serrations tend to last longer before needing to be resharpened than do plain edged blades. They are more difficult to sharpen than straight edges, but a number of products on the market have made sharpening serrations much easier than it used to be.
Ultimately, the combination edge is more a matter of personal taste. Some people prefer to have the entire edge serrated. Am not sure if that option is available in the knives you suggested in our earlier question. Many believe that for self defense, the fully serrated blade is the most useful. Others strictly prefer plain edges. Very few of the large "fighters" made by custom knifemakers have any serrations. Most are plain edge.
I personally prefer plain edged blades myself, but must admit that this may be partly due to difficulty in foreseeing the difficulties that might interfere with my way of doing things. They sure can cut. A lot of people feel that they are getting the best of both worlds when they buy a knife with a combo blade.
Serrations are not very "politically correct" in the US. Many "sheeple" perceive serrations to be weapon oriented. SOme airlines will not let you carry a knife with serrations on board when you are flying. So, they can be quite arduous to own. But, then again, the serrations really cut,and one can cut many jobs into short, quick work, instead of a long sawing/slicing session with a plain edge.
Good luck with your choice.