Here's some more tips from my adventures, Lex:
1. Use Dragoons on Desdemona (Yusnaan, Industrial District) and Gertrude (Luxerion, The Warren) drones to stagger them faster. Gertrude is harder to stagger, so wait till it goes for the "energy blast" move. Null-All Guard and Beat Down are great for Sentinel and Dragoon builds, especially once you synth Standby ATB Recovery and Committal on Level 5 versions of the spells.
2. I don't think it's a good idea to fight Bhuni+ on your "first run" of Hard Mode, you'll need to max out Ghostly Crown and Preta Crown (alternately pick up Warrior's Plume on the Last Day), as he alternates between ultimate magic and ultimate attacks, so you'll need Cyber Suit and Quiet Guardian working in tandem (same as with Aeronite). Also, Bhuni+ has "two phases" instead of the usual "three".
3. The sooner you play Hard Mode, the sooner you'll be able to upgrade weapons and use Limit Break to max your damage output. Making weapons upgrade isn't too hard, as you get materials from most monsters so long as you have Beggar's Beads (you can sell whatever spells you don't need, but I suggest synthing them all in to your best spells to reduce their ATB cost regardless). Equipping Victor's Rush will give you plenty of EP for Chronostasis in Hard Mode to farm.
4. Related to the above, the best places to farm items/EP/Gil are in Chaos Infusions, so try to only fight monsters in the middle of one... yeah it's harder on Hard Mode to do this, but most monsters aren't too bad once you get used to nuking them and staggering. Chaos' Revange "Quickstagger" will take care of most of the weak enemies really quick.
5. Later on, once you're done upgrading whatever shields and weapons you've made that you regularly use, you can sell the components for a hefty sum of Gil, useful for buying those other weapons and Garbs you've always wanted. Don't forget to fight Meonektons in Chaos Infusions (without Beggar's Beads equipped), as they drop a ton of Gil as well, as good as Cactuars on Day 13.
6. Archangeli have the best spells in the game (Elementa) but it's a pain in the neck to get the item to drop, so save your game just before entering the Cathedral if you aren't happy with your drops and want to maximize your synth odds. At one point I only had 4 Elementa spells and had to convert 2 spells in to an ability, and 2 more spells in to the SAME ability to get a Rare Synth.... the odds are staggering, and you have no idea how many times I reloaded my game save to do this...