Firstly get your terminology right. Pillaring is a shield pressure tactic the revolves around l cancelling a dair shining rinse and repeat. Some other things thrown into pillaring are double shining (2 JC shines on the ground) waveshining into another shine to chase an opponent who is being pushed away by your pillar. It is used to prevent grabs, break shields (rarely almost never happens against any competent player), break down a shield until a shine hits etc. etc.... It can be grabbed if done improperly, the proper way to pillar is to start with a rising dair, otherwise it is very "grabable" <----(not a word)
Now onto your actual question which revolves around shine combos. First off there is a good section on how to deal with marths in the stickied character matchup guide here in the falco forums, check it out, look at the matches for combo ideas. Marth is actually a great character for falco to combo, though not as good as fastfallers like captain falcon and fox (and falco of course
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). When you shine marth you need to chase him with a fullhop dair, or aeiral of your choice if you aren't trying to continue the combo.
Samus requires a completely different style of play than most characters because of her absurd floatiness, and up b out of shield. Samus cannot be pillared effectively because she can do an up b interrupting you, at any time she chooses. Samus requires a more defensive strategy for falco revolving highly around lasers (at least this is the way I prefer to play the match). Its good to keep racking up damage with lasers, and look for an opportunity to get samus into the air any time you possibly can, and keep her there! Here is an older video to give you an idea of how to play against a samus, though it presents a very extreme example of one style (specifically mathos' laser spamming) it should give you some ideas about how to go about the match, especially when you have ample room for movement.