I'm starting to realize I don't have a good grasp on spacing when it comes to lasers. Specifically, I often mess up recognizing what my good options are after I've connected a laser based on the spacing of the laser and the matchup.
So first of all, are there any good resources that discuss this?
Second, if I hit a laser and my opponent doesn't cc, is there a good rule of thumb for figuring out whether Falco can get nair/dair approach without the possibility of getting v stuffed?
You can't reliably approach after lasers, even on hit. You can only combo laser into nair if you hit a perfect laser (comes out the same frame you land), jump frame perfect, and nair frame perfect(first airborne frame). Wasting even 1 frame to dash means the opponent can shield. If you laser from further away you may be able to edge out an extra frame or 2 of advantage, but it will take you that much longer to reach them with a dash jump aerial anyway.
While we can generally consider laser -> aerial to be "unsafe", the reality is our opponents are human and imperfect, and they also can't shield all the time without opening themselves up to laser -> grab. If you feel like you caught the opponent off guard with your laser, you can try to hit them with an aerial before they react appropriately (either with dash away, shield, or a quick attack to stuff your SHFFL). Just keep in mind that if they are ready to react out of the laser and you commit to a SHFFL, you will either be at risk of getting DD grabbed or stuffed. SHFFLing a late aerial will never combo out of the laser, but it lets you set up shield pressure if they shield, and can also allow you to reasonable pressure spotdodges and rolls they might do in fear of a grab.
You really just have to look at each character one at a time and figure out their different ways of dealing with your options after laser, then when you play humans, identify their tendencies so you can abuse their habits. When you are playing better players, you will be able to use conditioning to your advantage. A bad player might not mix up his options after being laser grabbed 5 times in a row, or if he mixes up his options, he might not be aware of which are best suited to counter laser grab. Better players not only identify your attack patterns faster, but they are better at punishing you for not mixing it up as well. Sometimes mixing up your option is as simple as waiting a split second before doing whatever attack you did before, so don't feel like you have to make drastically different adjustments when they catch on to you. Simplest example is, if they spotdodge to avoid laser grab, just laser, dash back, visually confirm the spotdodge, then dash in and grab it on reaction.
Can you elaborate more on this? Are there specific instances in the match up where going high is more beneficial than staying on the ground other than to escape pressure? Also I think I heard somewhere that falco should be in the air when peach is on the ground and vice versa, I don't know how true it is and I generally prefer to stay on the ground but I'm interested in hearing your thoughts.
I'm not sure if this is what PP had in mind, but I find staying on the ground vs. Peach pretty risky when she has stage control. If she's setting up a float while you're under a side plat and you plan on catching her with a laser or jumping attack towards her before she throws out a fair, good luck. It's a really dangerous game, one I'd rather avoid by just FHing to the top plat before she gets her float set up. She can't punish FH on reaction, and even with a soft read (i.e. she positions herself to cover a FH to top plat), she has to worry about you driting/DJing away. Same concept applies to side plats, though they are obviously much easier for Peach to reach and punish you for landing on.
Falco definitely wants to be underneath Peach when she is airborne, which should be pretty obvious because that's the best way to shark underneath her and KEEP her in the air, but I don't think you necessarily want to be on the ground. Being on the plats is usually the best place to start sharking, and if you want to drop down to give yourself more time to bait out attacks/airdodges, then you always have that option.
As far as vice versa, I don't think it's that simple. Being above Peach can give you a lot of freedom, but I think there's always a lot of risk to giving her stage control, so ultimately I only jump above her when it feels less risky than being on the ground, as I described in the first paragraph. Once I'm dancing around platforms, my goal is almost always to find an angle back into stage control that she can't easily contest/trade with. The only exception to this is when she's at KO %. In that scenario, I'm more than happy to camp the top plat and just get ready to bair her jumping up to me or wavedash off/shai drop bair her if she misspaces herself on the ground. I think the key difference between those two situations is she is not content with poking with uair because she can't afford to trade or whiff the same way she can when she's at 0%.