Open 2 NT with 20 - 21 HCP and a somewhat balanced hand.  No need to have a stopped in every suit.  Tell "your story" to your partner.  Some will bid 2 NT with a singleton if it is an Ace.

2NT is an easy bid.  Honors in all suites.  

10 HCP give enough for game in NT.  With the void in Hearts use Staymen to check for Spades.  When Opener bids Hearts, bid 3 NT.  If Opener had 4 spades in addition to the Hearts they would bid 4 Spades.

3 NT is 9 tricks.  Game in Diamonds is 11 tricks.  With the Ace of Spades your partner can always get to the South hand.

With 7 HCP and no 4 card Major, just bid 3 NT and end the auction.

South bids Staymen.  When North bids Spades, bid 3 NT.

If using Transfers, South would bid 3 Diamonds.  North bids 3 Hearts.  South would then bid 2 NT showing game.  North would bid 4 Hearts to play.

Both are good contrracts for this hand.

With 13 HCP south thinks Slam.  First check for a Major suit fit with Staymen.  Once Spades is bid, ask for Aces using Standard Blackwood.

4 NT asks for Aces.

5 Hearts says 2 Aces. 

Without any kings in the South hand bid 6 Spades.

Open 2 NT even with the singleton Ace.  Tell your story.  

South bids 3 NT.  You would have to bid 4 Clubs.  3 Clubs would be Staymen.

South bids 3 Clubs Staymen.

With 5 Spades and a singleton, your had has improved.  Now a 12 points hand so check for Slam.  You can always stop at 5 Spades if an aces is missing.

5 Spades shows 3 Aces.

Bid 6 Spades.