perhaps...

What about a dotless i? Option-shift-b = ı

As well as the option of a dotless i, you can move the dot of the i to the right. This is actually in some old style fonts, derived from calligraphy, and it probably will look pretty "normal", if done with moderation.

You could try making the tittle fuse with a ball terminal.
I mean something like this (rough Photoshop comp):

The lovely Ingeborg has ligatures like that. (I'm actually not sure if there is a "W_i", but there's things like "V_i" and "N_i" at least in some weights.)

I have always assumed this is standard usage:

http://www.internetslang.com/IIRC.asp

But I wonder, which is the most authoritative, er, authority, on such matters?

(BTW, I wouldn't object to "Isn't It Really Cool" in my above sentence!)

Second one.

The detailing of the letters is a bit "large" for the finesse of the spacing, in particular the thickness of the stem to which the ball is attached.

This is not a display font, it is designed for small recognition of the characters as wholes; that is why the thin strokes of W are heavier than the joints of n, r and d: because those stems are part of the basic shape of the letters, whereas the thinned joints aren't, and are relatively slight because they will "fill in" with ink or visual bleed. However, at display size, the fine stems and serifs no longer have to strive for attention, and should be scaled back.

I would also consider overlapping some letters --i and n, d and s -- in the manner that the W and tittle have overlapped.

So, top one is original form and bottom one is enlarged tittle on "i", modified stem on "W", overlap between "i" and "n" and overlap between "d" and "s". I may have gone a bit too far the other way on the overlap between "d" and "s" and now (to my eyes) it seems to throw out the spacing of "s" and "o" and consequently the "o" and "r".
I tried matching the ball of the "r" with the updated tittle size but it looked plain wrong so I've stuck to the original tweak.

Critique?

I find the ball to be too low; it should visually align with with the top of the d and the serifs on the W.

"And merging W and i (which you suggested) doesn't?"
Indeed, to my eye this is less obtrusive, a less-strong binding (and more decorative); quite comparable to what you would see in say an "f_i" ligature. Whereas making serifs run into each other goes much further, in my eye/mind, into the direction of fusing letters together very strongly.* But hey, YMMV.

* Which I personally find bothersome when it's not consistent. For instance, I've always disliked the concept of the logo of the Swiss Coop supermarket chain – it relies on overlaps between rounds, which you can pull off in «coop»… until you have to do «bank coop» and get holes, which to me just makes the concept fail. Maybe I'm oversensitive, dunno.
http://de.wikipedia.org/wiki/Datei:Bank_Coop_logo.svg

So, spacing aside on this one for now (I'll come back to that contentious issue later), I've tried to equalize the height of the stem and tittle based on the advice from John and William.
I've attempted to mirror the drop of the "W" and level it off in the middle, between the top of the "W" and top of the "d".
I find optical alignment over actual alignment thoroughly depends on the designers perception so I fully expect a difference of opinion on this tweak.

I agree with William about the spacing. I think you could notch the tittle a bit to echo the notch on the r, but that's a pretty small point.

What do you think about this?:

@ nina
You're absolutely right about the problems I encounter when scaling the logotype. I've experimented and if I scale to less than 40mm in print (and 200px on screen), the characters join optically anyway. I'm reluctant to shave any more off the outer serifs as I don't want them to become smaller that the inner ones. If I do start to go down that road, it may have a negative knock-on effect as I'll have to alter all serifs to match the tweak. I don't want to potentially spoil something that is almost perfect for the sake of decimal points' worth of spacing (and my stubbornness!).
What I've done is simply increase the spacing on "i" and "n" and "d" and "s" to compensate although, looking at the rendered jpeg again, could perhaps push a little more (shown in figures 2 & 3).

@ John Nolan
Figure 1 shows the notch modification on the stem of "W" and tittle, which I completely agree with and have carelessly overlooked.

@Arno Enslin
It's an interesting concept as I can see the notch where the missing stem used to be could slip nicely into the space between the left hand serifs on the "i".
But... my eyes simply see a hybrid "X" with some sort of radioactivity induced growth or prosthesis!

How about this one?

@ Nick Shinn Time for closure.

Agreed. More than happy. Thank you for your input.