Getting the right multiplier for XP is heavily dependent on the place where you rest. It affects your experience points in two ways. Sleeping in a campsite will allow Ignio to cook up delicious meals that increase rate at which you gain XP points and sleeping in a hotel increases their value when they are applied to your character. Different locations provide more boosts with a price of course. Caravans or outposts give only 1.2x boost and cost 30 Gil, luxury hotels will give you twice or three times the experience multiplier but you will have to pay a lot more Gil for it. Here’s a quick breakdown of types of areas where you can sleep
1. Caravan (costs 30 Gil, gives a 1.2 XP increase).
2. Motel (Longwythe Rest Area, Old Lestallum, Lestallum’s Hotel, Taelpar Rest Area) – costs 300-500 Gil and gives a 1.5x XP multiplier.
3. Luxury hotels (Galdin Quay costs 10,000 Gil and gives a 2.0x XP multiplier boost, and Altissia costs 30,000 Gil with 3.0x XP multiplier).
The best thing is to balance Motels for 300 Gil (the amount is fairly easy to come by during your adventure). When you hit late game, save up some cash and go on a spree of quests and missions and cash it all in on a luxury hotel for best gains.
Because you can’t visit Altissia until the second half of the game, it’s worth doing this. Another important note is to rest and get XP multipliers BEFORE THE END OF A CHAPTER, where it is automatically calculated together without any bonuses. With some chapters this is unavoidable, but if you have the opportunity, be sure to sleep somewhere.
Eating XP Boosting Food
While the above mentioned method is the best way to rest, you can combine the benefit by leveling up at a hotel and then immediately going camping or eating before going for any quests. This means you never waste any leveling up at a campsite and it still lets you benefit from earning XP at a faster pace. The gains from food are only of limited duration and work on monster-based XP gains, but if you know that you are to head into a dangerous territory, it’s definitely worth it.
The easiest and most efficient is called the Fat Chocobo Triple-Decker that’s unlocked by completing “A Feathery Feast” quest at Wiz’s Chocobo Farm, gives you a desirable 50% boost for only 1,200 Gil. Eating it will even unlock the recipe for the Stacked Ham Sandwich will alike effects for Ignis to cook.
Equipping the Moogle Charm will give you a 20% XP boost while wearing it, but this can be found in late game dungeons and tombs by which you are probably a high enough level to not get many of their benefits. Completing side quests while on your story will give you a lot of XP.