The 2008 Giant Boulder SE, for both Canada and the United States, are identical. However, there are two different colours. Each of the two colours have minor differences. I was wondering a couple things.

1) The seat for the Dark Blue/Blue version is the Unity Groove Plus. The seat for the Gray/Black version is is Giant DJ. What is the difference between these seats? I cannot seem to find any literature or more photos of them. Does anyone who's seen or tried both of them prefer one of the other?

2) The tires for the Dark Blue/Blue version are called "MTB Trail". The tires for the Gray/Black version are called "Kenda K-Rad. I have read that the Kenda K-Rad are good for urban riding and dry off-road riding. Is this correct? Also, I could not find anything out about the "MTB Trail" tires. Are the just generic Giant brand? Which tires are better, and for what?

3) The colours: Dark Blue/Blue and Gray/Black. From the stock image on the Giant website, I like the look of the Dark Blue/Blue bike the best. I was wondering, does anyone have any alternative images of these bikes? I was to see better what they look like.

Frame Size

4) My Local Bike Shop has one of the Black/Gray and one of the Dark Blue/Blue bikes coming in. The Black/Gray version should arrive next week. However, the Dark Blue/Blue version won't be here until near the end of April. I have already purchased the bike, but I have the choice of which model I want. However, I was concerned about something. He ordered two 20" frames (L) and I was wondering if this might be too big for me. I am only 5"8 with a weight of around 170-175 lbs. I have been upwards to 200 lbs before though. Should I be getting an 18" frame, or will the 20" be fine?

Thanks!