The easiest for the US is coinbase.com. Unless you want to buy a lot. But they are not an exchange so you can't setup buy/sell orders.

Not really if you want to trade. They are playing safe instead of having balances in USD and BTC so that you don't need an ACH for each buy/sell, which takes a week.

Bitstamp.net is excellent, at least in Europe (usually one day SEPA transfers). It also has modern responsive interface and works very well. Localbitcoins.com is another good one, it's a P2P exchange where you can also buy/sell bitcoins with cash.

I prefer localbitcoin and bitcoin-otc, but I do have an verified account in MtGox.

I wouldn't trust Gox as far as I could throw a piano right now.

I've been waiting more than 24 hours for a BTC withdrawal. It's not even showing up on blockchain.info yet. Search the forums there are a lot of people this is happening to. Some with more than 3 days.

I'd be EXTREMELY cautious and suspicious about Mt.Gox right now. Make very sure you can get your BTC/USD out of Gox before you trust it.

24 hours? but did you pay a fee? sometimes if you don't pay a fee it takes long time until some block includes your transaction, and specially when the difficulty of the network is high (like now).

3 days? People haven't been able to withdraw BTC to USD in months as far as I was aware. http://www.reddit.com/r/mtgox

Not BTC to USD. Just plain BTC to my wallet.

This is happening to a lot of people.

https://bitcointalk.org/index.php?topic=324918.60

I have used localbitcoins.com a few times to buy bitcoins, and have been happy. Remember to use the site's escrow though.

campbx.com within the United States. They do 2 day ACH withdraws for $2 and same day domestic wire transfers for $20. After bitfloor closed down I switched and have been very happy.

bitcoin.de if you are in Germany.