Hi and welcome! First thing to think about is spacing. With Chase cards, it's recommended to space cards about 90 days apart. Since P1 and P2 both just got a card, you have a bit of time before you might want to apply for another. This is great time to start to map things out.
You mentioned a few aspirations- 2022 Greece and SW companion pass. IRT 2022 Greece, when booking award flights, especially business or first class, you usually need about a year in advance to book, which means you need those points already accrued at least a year prior. Given the wonky travel situation, you may find some award availability less than a year in advance, but perhaps not. I like to use awardhacker (It's not perfect, but good) to help me figure out what airline program I would use for points- so then I can try to get a card where I can transfer/earn points for that program. But, you really do have to check things out to see how much you'd pay in points and taxes vary quite a bit between programs, as does award seat availability. So you'll likely need to do some research for this!
SW companion pass. Do some research on the best timing of this- usually towards the end of the year, so that you are earning companion pass for 2022 and 2023. Keep this timing in mind when you are mapping out what cards to get next.
Also consider business cards if you have a business, like selling things on facebook, etc.
I'm sure others will chime in with some advice on specific cards. Doctor of Credit is a favorite site for good cc offerings. Remember, P1 and P2 should always send support links to each other, to earn additional points when applying for a card. Amex is nice for that bc if you have ANY Amex card, you can support each other to any other Amex card. If it's a card P1 or P2 don't have, you can always show your love to a friend here by joining our reddit group. You should receive a message to join if you haven't already.
Again, welcome, and keep asking questions!