How to make a good and secure spiral stairway

Basically I want redo the stairway that leads to my underground area. The way this is set up now is just block after block going down. Going upwards is a pain because you have to jump.

Now my underground area is at bedrock, and my 'living' area it at lever 50, so that is quite a distance.

I want to make the stairway shorter also, so I was thinking about kind of a spiral stairway. I have been trying this, but I can not seem to figure this out correctly. I keep bumping my head or I have to leave a gap in the middle, which when you fall off you die.

Does anyone have a good design for this ?

Here's my 7x7 spiral starcase design (9x9 if you include the outer walls).

Overhead view:

W = outer wall
1, 2, 3, 4 are landings
S = stairs
(space) = open - mine it out or don't at your preference.
X = floorblocks in horizontal views.

WWWWWWWWW
W11SSS22W
W11SSS22W
WSS   SSW
WSS   SSW
WSS   SSW
W44SSS33W
W44SSS33W
WWWWWWWWW

Start with a 2x2x2 landing. Dig a 2x2 tunnel forward 5 squares (landing is now 2x7x2). Remove floor 2x5x1, then floor 2x4x1 then floor 2x3x1. Notice the lower landing is 2x3 before stairs are added.

Here's a side view before stairs are added.

WXXXXXXXW
W       W
W       W
W11     W
W  X    W
W   X   W
W    X22W

Now with stairs added, the lower landing is 2x2

WXXXXXXXW
W       W
W       W
W11S    W
W  XS   W
W   XS  W
W    X22W

Turn 90 degrees and repeat until bedrock.

In my version, I place torches on the floor in corners, I mine the 8 squares around the center, but leave a single block central pillar in the middle from top to bottom.

In the original version, I started at two opposite corners and made a double spiral staircase. While this does find all the minerals, it's a lot of extra work. I had hoped in the future to improve the design to allow a waterslide down one, and a minecart ride up the other.

If you use a central column and alternating half blocks and full blocks you'll end up with a spiral staircase you can walk up and down comfortably and one you won't be able to fall off.

As you need a three high space to avoid banging you head you will need to have five blocks on each side of the square going up:

H F H F H
F C C C F
H C C C H
F C C C F
H F H F H

(bad plan view)

        HH
      FF
    HHFF
  FF
HHFF 

(bad side view)

If you make it two block wide it will be easier to climb and descend and you might be able to make the central column look like this:

  C
C C C
  C

Use stairs in a 3x3 pattern with a central column:

As you can see you will need to make it at least 4 high else you wont be able to get up or down the staircase (you will keep hitting your head on the ceiling). Also make the corner stairs point towards you when you are going up (as in the screenshot)

I've never had any problems running up stairs in this design.