Well, you know I am opinionate....So I will give mine. Bridge wasn't played here, and you will not learn much from studying the given auctions. Of the three, the dislike the least is auction number 1 (which ended in 4S). That one was closest to defendable.
AUCTION ONE
West North East South
Pass Pass 1
♠ Pass
2
♠ Pass 4
♠ Pass
Pass Pass
1S = a typical maximum 1S opening bid.
2S = 2/1 "constructive raise"
4S = burying head in ths sand a little bit. This is an underbid, but not horrible underbid.
I would make two slam tries with the EAST hand starting with 3
♣. Partner will id 3
♥ and I will try 4
♦, showing 3
♣ as a cue-bid. Bidding more depends upon WEST, If he bids 4
♠ end of investigation. If he bids 5
♠ I will bid six, if he bids 4
♥ mild slam try, I think we are there. I think gettng to 4
♠ isn't so bad here, I just think you have to make at least ONE Try for slam, if not two.. REMEMBER your partner 2S bid was limited and descptive, so 4S is NEVER A SLAM TRY, it is a signoff.....no matter how strong it sounds.
AUCTION TWO...
West North East South
Pass Pass 1
♣ Pass
1NT Pass 4NT Pass
5
♦ Pass 7
♠ Pass
Pass Pass
This is not seroius bridge, this is probably not even real bridge. No doubt 1
♣ was precision or similar, and 1NT looks like blanced 8 to something. 4NT should be quantative asking for slam if on "top". IF this is precision, I suspect balanced 9 with 4333 is minimum, not max. West responds he has one ace and EAST bids a GRAND SLAM in spades. The auction is not real, makes no sense in any bridge sense. Either EAST needed a huge swing immediately and was taking a flyer, or is an absolute beginner who gets over excited when seeing a moderately good hand, or something evil was going on. DO NOT EMULATE this bidding...
West North East South
Pass Pass 2
♣ Pass
2
♦ Pass 2
♠ Pass
4NT Pass 5
♣ Pass
6
♠ Pass Pass Pass
OK here EAST thinks his hand is worth a strong opening two bid, despite his only 18 hcp. I happen to agree with this evaluation IF YOU PLAY 2H response to 2C as instant double negative with no trick. So you can get out in 2H or 2S with hands like this. 2
♦ was waiting, and 2
♠ was a spade suit (lets hope it can'[t be 4144 hand pattern... because WEST takes the bull by the horns and forces to 6
♠ without further to do. I think WEST's bidding here is also very bad. Assume EAST had a 22 point hand with 5 spapdes and stiff heart. You are in a 31 point slam. Now, after a 2
♣ openign bid, I am thinking SLAM with WEST, but I am not going to FORCE to slam.
A typical 2/1 auction might be (opponents passing)
1S-2S-3C-3H-4D-4H-4NT-5D-5H-5S-6S-all pass
A typical 2/1 auction with ACOL two bids in majors allowed in 2C
2C-2D-2S-3S-4N-5D-6S <<--- 3S shows 2.5+ tricks for spades, with 0 you would bid 2H not 2D, with 1 or 2 you would jump to 4S over 2S.