Do we really need anything more than 8" woofer and 1" tweeter for medium size room?

Whatever else they might be, they won't do bass. Without sufficient bass no speaker can be called phenomenal. With a pair of great subs, then it may be quite a sound, I don't know.
And we are not talking about prices and value, cost is no object in this discussion.

But since you mentioned monitors, I read that LaHave speakers, I think I got the name right, from Canada sound extremely good, but again not enough bass. Bass is the most difficult thing to get right, as I understand it. Not that the rest is easy, it is not.

Inna

What is sufficient bass? Will the room vibrate? Will it be lightening fast? will it be fat and slow?

For me it just needs to be satisfying, I am not trying to impress anyone I just want to enjoy listening. Bass is so tied into to room response that no full range loudspeaker can provide the maximum amount of bass that room can handle without the danger of going over the top. 

So a bass that satisfies is what I require to describe a speaker as  phenomenal, if it has phenomenal mid-range and highs and is cohesive and fast and disappears. 

I cannot imagine (unless you have a very small room) that a pair of 8" woofers (in a speaker - not a dedicated subwoofer) will be anywhere near enough bass to really create a full range sound.  If you have a large 2-way bookshelf or even floorstander with 8" mid-woofers in them, there is no way that they will be hitting down to 25hz or lower in your room.  Even adding a dedicated powered 8" subwoofer (or a pair) will still not carry you down to the very low frequencies.  Now you may not listen to the types of music that even contain these frequencies, which is a different thing, but when you listen to some of the music that I do, there is A LOT happening down low that I never even knew was there until I bought a subwoofer like the G1.  Simple physics... if you want to reach really deep and have control at the same time, you really need a large sealed box, large woofer, and pretty decent amount of power.  And an 8" Sunfire subwoofer.... ummmm, no.

If I wanted to add subs I too would go with at least 10", but they would have to be fast enough. I keep hearing praise of JL Audio subs, and REL is well-known as a generally good choice for music.