To add my opinion, I would like to key in on two things:

And:

You don't have any specific plans and your time horizon is several years out.

Your biggest concern, at this point, should probably be "devaluation risk". So much could happen in the next few years with any of these currencies to make them worth less (or worthless).

Consider something like this:

1. List out your primary airline options (will probably be DL, AA, UA, US) and hotel
2. Look at the current award charts to determine what your biggest dream could possibly be - at worst, just look up the highest possible redemption amount on the chart
3. Figure out a combination of earning (CC signup, direct CC spending, third party currency like Ultimate Rewards)
4. Build a calendar that balances signups and your everyday spending to hit all your possible aspirational goals within your 2-4 year time frame (with your level of spend, it's probably something like a new CC every month or two plus one or two with annual tiered spending goals)
5. Adjust every few months to take account of devaluation

Then also make sure you maximize your current experience, by showing loyalty to an airline, hotel, and car rental partner to earn their own elite status.

Since you are new to this, you will probably make terrible mistakes. For example, you might earn top tier elite status on AA then decide you hate connecting at DFW, or you hate Marriott executive lounges, or whatever. So allow for the possibility of status match in your second year to try something else.