Ways to visualize multiple large LiDAR tiles?

Your computer has plenty of spec:

Develop a full or partial disk cache whenever possible. Disk caches allow data to be pre-rendered for optimum ArcGlobe/ArcScene display performance. Store ArcSDE/ArcScene data sets using the Cube projection This will avoid pyramid resampling and data reprojection for ArcGlobe.

http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?id=3482&pid=3453&topicname=Optimizing_ArcScene

http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=Disk_cache_formats_in_ArcGlobe

Other helpful ArcGIS tips... (includes AMD Processors) http://mapperz.blogspot.com/2007/02/esri-arcgis-92-tips-and-tricks.html ArcGIS/Utilities/ArcMap Advanced Settings Use with Administrator Privileges.

ArcScene is a 32bit application and not a multi-threaded one so there are limits.

You could try terrain datasets.

You could also try generalizing your data.

In lidar world, those aren't even large tiles! Rather than reiterate a snazzy presentation from the latest ESRI 2010 user conference, I'll point you to the pdf of the presentation.

It basically walks you through how to quickly pull point cloud data into a 2.5d rasterized dataset, instead of interpolating the mass points (important if using the ground dataset, since it's already interpolated from the rest of the cloud and usually fairly dense anyway).

This is especially useful if you don't want to spend the time waiting for data to load into a Terrain dataset.

[EDIT] A short time later, ESRI has the LAS dataset datatype. If you're spending any amount of time with Lidar, it's worth doing what you can to meet the license requirements for operating with this datatype since it can save you a lot of time and effort moving data in and out of ArcGIS.