Managing the SolPart menu is a challenge at times.. because it does offer alot of different configurations, some better with browsers than others, but there are ways of displaying content without using the menu itself. And there are third party products around that I think do a great job, but while some people rave about the removal of the JS file (which is cached first time it's loaded) the files have alot of code within in them that make loading the pages.
Then we have browser compatibilty - wow, that's a can of worms itself.
You can turn off icons by having this in your css code - where the arrows / icons is mentioned - display: none; that turns off the icons from displaying and arrows.
There are other menus around - http://www.telerik.com/dnn - at a cost of course but you can do alot with it.
Then there is component art - http://www.componentart.com - again at a charge but it's very fleixible once you can grasp how the skinning elements work -
I found both products are hard to follow at times and load the pages with alot of code but are very browser compliant so if it's important - then they are options.
There are third party css menus - http://www.houseofnuke.com has one - and it's a css based flyout. It seems to work nicely - but not sure how it works with spiders - so in fact, no able to tell you about the virtues of menus and spiders.
There is the http://www.inventua.com side and top menu - does not offer flyouts but is very DNN & Browser friendly.
There is also a very slick little product - http://www.oliverhine.com he's got a sitemap module - but he's using the http://www.devmansion.com menu wrapped into this module and I think it's quite cool.
You can also experiment with the breadcrumb and links skinobjects -I've done a range of sites for a client where we put in some very nice effects with link, active, over and over state images on a site that has no solpart menu - it looks great..
I think alot of people get bogged down in trying to make solpart into something it's not - when they forget that it's a brilliant part of dnn - a dynamic, skinnable menu, which has it's own set of challenges.. and even today - it takes up a large part of our skin development to make right.
I work in ascx mode - because with solplart you need to apply code to the skin as well as the css file to reflect the changes so you can see that if you're not familiar with this, you can't see the results as they may not be applied if working in html mode and xml mode, unless you have coded the xml file correclty which I find tedious when doing complex menu skinning.
This is only a bit of a rambling of thoughts I know, but I have tried to get some thoughts I have on things so you can explore some different options rather than get bogged down with the burden of learning the ins and outs of the menu.
I hope this gives you some insight - and also in reference to sites spidering your sites - I find that utilising the links skinobject really does help go a long way and on all my pages in my site - (well the important ones) I have the Inventua side menu skinned a little bit and used the copy module to get all the child pages on there displaying and hopefully helping with getting it spidered.
There you have it - I"m off to have a cup of tea - before I move to the harder stuff.. I really appreciate thoughts like yours and many others - it helps me understand where I can be of assistance, since I don't code at all, so not of real dnn core team value when it comes to contributing, but I think with questions and thoughts like yours I can come up with some other things for you to think about and discover.
Thanks for your post!
Nina Meiers