I'm the kinda guy that would buy the most AVR I can allow myself to afford. Of your listed option, the 2080, especially if you see yourself even potentially beginning to flirt with Atmos... but if ever you were to do that... you should consider 5.2.4... the rear surrounds can be lived without according to many. (I love my rears though, so 11-channels for me, please!)
Anyway... buying the AVR is more about the feature set and ergonomics of the machine. Make certain you get the connections you will need to manage your rig over time. Things like pre-outs, if ever you were to add external amplification, are a necessity in my book. Analog inputs, maybe not so much (comparing Denon to Marantz in that case).
Bi-Amping is a waste.
You can do it, but it only costs you money, and in terms of using extra channels of your AVR, it costs you potential power. (The Amp Stage of your AVR will have to work harder to send two signals to your mains). Though some claim benefit from this, as well as Bi-Wiring, it is generally accepted to be of no noticeable advantage.
In short... Buy the best AVR you can afford with an eye towards the features and usability you may want over time.
Don't waste energy on Bi-Amping. I looked hard at it. I am not doing it. Research it if you want, there is a lot out there on the topic.
Oh... power... Klipsch speakers are sensitive, though not as much as they claim... regadless, if you go the route of the 2080, you will have more than you need to capably handle those speakers. Using a more realistic 92dB sensitivity, 64w will clear Reference Level Dynamic peak at most LPs with those speakers. That is movie theater loud. If you listen like that all the time, you will go deaf.
Case in point... I do most of my listening at -15 - -10dB... I rarely use more than say 1-4w to drive any of my channels. Sometimes I do turn it up, and I have the headroom available to hit that 105dB Reference Level Dynamic Peak at my LP. How often have I done so? Maybe once in the 6mos I've owned my system.
Hope this helps.
