Jesus himself gives us a good description of how his return will be in Matthew 24.
See also
Mark 13:26
Mark 14:62
Revelation 1:7
Matthew 24 23-40
23Then if any man shall say unto you, Lo, here is Christ, or there; believe it not. 24For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect.
25Behold, I have told you before.
26Wherefore if they shall say unto you, Behold, he is in the desert; go not forth: behold, he is in the secret chambers; believe it not.
27For as the lightning cometh out of the east, and shineth even unto the west; so shall also the coming of the Son of man be.
28For wheresoever the carcase is, there will the eagles be gathered together.
29Immediately after the tribulation of those days shall the sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken:
30And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.
Those who believes in Christ and know his words will be better equipped to recognize him. If we do not study the word and know his teachings we can more easily be led astray and be decieved. We will know the false prophets by their fruits (Matthew 7:16).
John 10 4-8
4And when he putteth forth his own sheep, he goeth before them, and the sheep follow him: for they know his voice. 5And a stranger will they not follow, but will flee from him: for they know not the voice of strangers.
6This parable spake Jesus unto them: but they understood not what things they were which he spake unto them. 7Then said Jesus unto them again, Verily, verily, I say unto you, I am the door of the sheep.
8All that ever came before me are thieves and robbers: but the sheep did not hear them.
As for the passage where he walkes with two of the diciples and they do not recognize him, the answer is given here:
Luke 24:16
16But their eyes were holden that they should not know him.
And later
Luke 24 30:31
30And it came to pass, as he sat at meat with them, he took bread, and blessed it, and brake, and gave to them.
31And their eyes were opened, and they knew him; and he vanished out of their sight.
It seems that Jesus choose to close their eyes so that they would not know him. Maybe it isn't so much about us recognizing him but it is he who open our eyes so that we recognize him?
If Jesus was here today and wanted you to recognize him you would, but if he didn't your eyes would probably also be closed.